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EXPERIMENTAL  RESEARCHES 


CONCERiriljrG  THE 


PHILOSOPHY 


OF 


PERMANENT   COLOURS; 

AND  THE 

BEST  MEANS  OF  PRODUCING  THEM, 

BT 

(      DYEING,  CALICO  PRINTING,  ^c. 


<L 


BY  EDWARD  BANCROFT,  M.  D. 

TEtLOW  OF  THE  ROTAL  SOCIETY  OF  LONDON,  AND  OF  THE  AMERICAN  ACADEMl 
OF  ARTS  AND   SCIENCES,  OJ  THE  STATE  OF  MASSACHUSETTS    BAT. 


*♦  Get  art  (de  la  teinture)  est  un  des  plus  utiles  et  des  plus  merveilleux  qu^ou 
:onnoisse;  et  si  quelque  un  pent  inspirer  un  noble  orgueil  d  I'hommey  c'est  celiH  Id: 
aon  seulment  il  a  procure  le  moyen  de  suivre  et  d'imiter  la  nature  dans  la  lichesse 
jtl'eclat  des  couleurs;  mais  il  paroit  I'avoir  surpasse  en  donnant  plus  d'eclat,  plus 
le  fixite  et  plus  de  solidit^  aux  couleurs  fugaces  et  passageres  dont  elle  a  reretn 
ous  les  corps  qui  composent  ce  globe." 

Chaptae,  El^mens  de  Chimie,  torn.  iii.  p.  18?. 


^  VOL.1. 


i 


PHILADELPHIA: 

PUBLISHED  BY  THOMAS  DOBSON,  AT  THE  STONE  HOUSE, 

No.  41,  SOUTH  SECOND  STREET. 

William  Fry,  Printer. 

1814. 


CONTENTS  OF  VOL.  I. 


Page 

Introduction,  concerning  the  origin  and  progress  of  dyeing 
and  calico  printing         -  -         -         -         -         -        xiii 

PART  I. 

Chap.  I. — Of  the  permanent  colours  of  natural  bodies         -  1 

Chap.  II. — Of  the  composition  and  structure  of  the  fibres  of 
wool,  silk,  cotton,  and  linen 62 

Chap.  III. — Of  the  different  kinds  and  properties  of  colour- 
ing matter  employed  in  dyeing,  calico-printing,  &c.        -         82 

Chap.  IV. — Of  substantive  animal  colours,  and  principally  of 
the  Tyrian  purple 89 

Chap.  V. — Oi  vegetable  substantive  colours,  and  principally  of 
indigo,  and  the  plants  affording  it,  or  a  similar  colour      -      122 

(^HAP.  VI. — Oi  mineral  substantive  coloMXs,         ...        2 


ji> 


PART  11. 

Chap.  I. — Of  adjective  colours  generally,  and  their  basesj 
"with  an  illustration  of  their  effects  upon  each  other,  as  ex- 
emplified by  Oriental  and  European  calico-printing        -       253 

Chap.  II. — Of  adjective  colours  from  European  insects,  and 
principally  from  the  kermes,  or  coccus  illicis,  Linn.        -       292 

Chap.  III. — Of  the  natural  history  of  cochineal        -         -         305 

Chap.  IV. — Of  the  properties  and  uses  of  cochineal;  with  an 
account  of  new  observations  and  experiments,  calculated  to 
improve  the  scarlet  dye  -  -         -  -  -  331 


Digitized  by  the  Internet  Archive 

i n  2B01  with  .f u nd i ng  fro m 

IVIicrosoft  Corporation 


http://www.archive.org/details/experimentalrese01bancrich 


PREFACE 


The  arts  of  dyeing  and  calico-printing,  having  at- 
tracted my  particular  attention  so  early  as  the  year 
1769,  I  published  a  volume  in  1794,  under  the  title  of 
Experimental  Researches  concerning  the  Philosophy 
of  Permanent  Colours,  &c.,  intending  that  it  should 
have  been  followed  by  a  second,  as  soon  as  my  other 
avocations  would  allow  me  to  prepare  it  for  the  press. 
But  my  progress  in  that  work  was  unexpectedly  re- 
tarded, until  the  year  1799,  when  a  bill,  which  had 
passed  the  House  of  Commons  for  granting  me  a  more 
adequate  remuneration  for  some  of  my  former  discove- 
ries, having  been  lost  in  the  House  of  Lords,  (from 
causes  mentioned  in  the  second  volume  of  this  work, 
Part  n.  Chap.  2,)  it  became  my  duty  to  withdraw  my  at- 
tention from  the  intended  publication,  (at  least  for  some 
time,)  and  employ  it  upon  matters  which  seemed  more 
likely  to  compensate  the  severe  disappointment  I  had 
thus  suffered.  For  this  purpose  I  made  two  voyages, 
one  to  North,  and  the  other  to  South  America,  in  both 
of  which  my  expectations  were  frustrated  by  ill  health: 
and  having  then  attained  an  age  but  little  suited  to  a 
renewal  of  such  undertakings,  I  resumed,  and  have  for 
several  years  continued  those  pursuits  which  have  ter- 
minated  in  this  work;  and  I  did  it  with  the  greater  ala- 
crity, upon  finding,  after  the  whole  edition  (of  one 
thousand  copies)  of  my  former  publication  had  been 
exhausted,  that  second-hand  copies,  when  they  could 
Vol.  I.  a 


ii  Preface, 

be  procured,  were  currently  sold,  (though  without  anj 
benefit  to  me,)  for  six  times  their  original  price. 

It  may  be  readily  conceived,  that  the  numerous  che- 
mical discoveries  produced  during  nineteen  years,  which 
have  nearly  elapsed  since  the  publication  of  my  former 
volume,  must  have  given  occasion  for  many  additions 
and  corrections;  especially  as,  during  this  interval,  I 
have  made  several  thousands  of  experiments  relating 
to  the  subjects  of  it.  For  a  considerable  time,  I  hoped 
and  expected  that  these  additions  and  corrections  might 
have  been  printed  separately,  to  suit  and  improve  that 
volume;  but  they  have  ultimately  been  found  so  nume- 
rous, and  interspersed  through  so  many  of  its  pages, 
that  nothing  but  confusion  and  useless  expense  could 
have  resulted  from  such  an  endeavour  to  accommo- 
date the  possessors  of  it,  and  enable  them  to  assort  and 
connect  it  with  the  second  volume  of  my  present  work; 
especially  as  an  alteration  in  the  arrangement  of  some 
parts  of  it  had  become  expedient.  Their  condition, 
however,  will  only  be  such  as  is  commonly  produced, 
by  the  publication  of  a  new  and  improved  edition  of 
any  book. 

In  arranging  the  subjects  of  this  work,  it  would  have 
appeared  most  natural,  to  treat  separately  of  each  co- 
lour, and  of  the  means  of  producing  it;  but  as  the  same 
colouring  matter,  by  changing  the  basis  or  chemical 
agents  employed  with  it,  will  often  produce  very  diffe- 
rent colours,  this  course  of  proceeding  must  have  occar 
sioned  many  repetitions,  and  a  frequent  recurrence  to 
the  same  colouring  matter.  I  have,  therefore,  made  ano- 
ther arrangement,  which  will,  I  think,  enable  me  to 
communicate  my  ideas  intelligibly,  with  the  fewest  repe- 
titions, and  without  separating  matters  essentially  con- 
nected to  each  other:  and  in  doing  this,  I  have  endea- 


Preface,  iii 

voiired  to  avoid  minute  descriptions  of  such  manual 
and  mechanical  operations  in  dyeing  and  calico-print- 
ing, as  are  in  common  use,  and  not  connected  with  the 
principles  of  the  art,  because  the  artists  know  these 
operations  already,  and  to  mere  speculative  or  philoso- 
phical readers,  a  knowledge  of  them  would  be  useless. 

I  have,  in  the  course  of  this  work,  commonly  adopted 
the  language,  and,  with  a  few  exceptions,  the  principles 
or  explanations  of  modern  chemistry,  not  as  being  wholly 
unobjectionable,  but  as  according  best  with  known 
facts,  and  being  most  likely  to  become  parts  of  a  more 
perfect  system,  when  future  discoveries  shall  have  laid  a 
sufficient  foundation  for  the  construction  of  one.  I  have 
not,  however,  been  convinced  of  the  expediency  of 
adopting  some  of  the  opinions  recently  promulgated  by 
Sir  Humphrey  Davy;  though  1  hope  and  believe,  that  I 
am  properly  disposed  to  admire  his  extraordinary  talents, 
and  acknowledge  the  important  additions  made  by  him 
to  chemical  science.  This  is  not  the  place  to  discuss, 
and,  therefore,  it  would  be  improper  to  dispute  any  of 
his  facts;  but  I  hope  it  may  not  be  deemed  improper  for 
me  to  mention  a  few  of  the  objections  to  which  some  of 
his  conclusions  seem  liable. 

He  supposes  himself  to  have  proved  that  the  fixed 
alkalies  (and  several  of  the  earths)  are  metals  combined 
with  oxygene,  or,  in  other  words,  metallic  oxides;  and 
that  when  the  oxygene  has  been  separated  by  the  power- 
ful agency  of  opposite  electricities,  from  the  bases  of 
these  alkalies,  the  latter  are  reduced,  each  to  its  proper 
metallic  state,  and  though  the  supposed  metallic  globules 
so  produced,  cannot  be  retained  in  this  state  for  a  single 
minute  without  burning,  and  again  becoming  potash  and 
soda,  and  are  besides  much  lighter  than  water,  he  has 
thought  it  right  to  consider  and  arrange  them  as  metals. 


iv  Preface^ 

under  the  names  of  potassium  and  sodium.*  He,  (Sir 
H.  Davy,)  admits  that  "  a  considerable  degree  ol  speci- 
fie  gravity  was  formerly  considered  as  an  essential ch^iVdiC- 
ter  of  metallic  substances,  but  (he  adds)  1  have  discovei  ed 
bodies  lighter  even  than  water,  which  agree  in  all  other 
essential  qualities  with  metals,  and  wliich  consequently 
must  be  arranged  with  them."  See  "  Elements  ol  Che- 
mical Philosophy,"  p.  319.  How  it  should  follow  'hat 
bodies  which  agree  with  metals  in  all  but  one  essential 
character,  **  musf'  be  arranged  with  them,  I  am  unable 
to  conceive:  for  to  my  understanding,  an  opposite  infe- 
rence seems  the  most  natural,  and,  indeed,  the  only  al- 
lowable one.  But  is  it  true  that  the  bodies  in  question 
do  really  possess  all  the  other  characters  which  are  deem- 
ed essential  to  the  constitution  of  a  metal?  Is  not  the 
strong  propensity  of  potassium  and  sodium  to  burn  in- 
stantaneously in  the  air,  and  as  instantaneously  to  de- 
compose water,  without  acquiring,  in  either  case,  the 
properties  of  metallic  oxides,  at  variance  with  all  former 
ideas  of  the  nature  and  essential  characters  of  a  metal? 
Even  the  shining  quality  of  these  supposed  metals,  which 
more  than  any  thing  else  seems  to  give  them  a  metallic 
appearance,  belongs  equally  to  petroleum,  when  diffused 
upon  the  surface  of  water,  and  to  indigo  when  dissolved 
for  topical  application  by  calico-printers,  as  is  hereafter 
described.  Sir  H.  Davy  has  admitted  (p.  321  of  his  Ele- 
ments) that  "  the  common  metals,  in  consequence  of 
their  fusibility,  malleability,  hardness,  and  durability, 
have  been  the  most  important  instruments  of  the  arts;" 
and  that  **  the  uses  of  ihem  have  been  essential  to  the 
progress  of  civilization:"  and,  after  such  an  admission, 

*  Gay  Lusac,  and  Thenard,  have  supposed  these  productions  to 
be  compounds  of  potash  and  soda  with  hydrogene,  (or  hydiures) 
and  Curadau  has  thought  them  to  be  compounds  of  charcoal,  or 
iibarcoal  and  hydrogene,  with  potash  and  soda. 


Preface,  v 

it  may,  T  think,  be  reasonably  asked,  why  they  are  to  be 
confounded  with  matters  which  have  none  of  these  cha^ 
racters? 

Surely,  if  it  be  expedient  (which  I  do  not  perceive)  to 
comprehend  things  so  dissimilar,  under  one  common  or 
general  denomination,  it  would  be  much  more  convenient 
to  invent  a  new  name  for  that  purpose,  and  allow  us  to 
designate  matters  of  such  high  importance  as  the  metals, 
properly  so  called,  by  that  which  has  been  so  long  ap- 
prnpriated  to  them.  To  confound,  by  one  appellation, 
substances  so  unlike  each  other,  as  those  commonly 
called  metals,  earths,  and  salts,  must  be  highly  inconve- 
nient for  the  ordinary  purposes  of  life,  as  well  as  for  the 
operations  of  human  intellect;  and  it  must  be  no  small 
addition  to  the  evils  of  this  confounding,  to  have  it  ex- 
tended even  to  water,  and  to  that  fluid  of  which  our 
atmosphere  chiefly  consists,  nitrogene;  both  of  which,  as 
a  consequence  of  these  doctrines,  are  to  be  deemed  me- 
tallic  oxides  (i.  e.  of  hydrogene.)  It  cannot,  I  think,  be 
necessary  for  the  advancement  of  science,  that  we  should 
thus  perplex  our  language  and  ideas,  and  subvert  those 
distinctions  which  have  long  regulated  the  actions  and 
opinions  of  mankind;  and  I  have,  therefore,  abstained 
from  these  innovations  in  the  following  pages.  There  is, 
indeed,  an  additional  reason  for  not  considering  in  this 
work  the  alkalies  as  metallic  oxides;  which  is,  that  their 
effects  in  dyeing  are  as  opposite  as  possible  to  those  of  the 
oxides  of  metals,  properly  so  called:  and  in  regard  to 
alumina,  (or  the  earth  of  alum)  which  is  supposed  to 
contain  a  peculiar  metal,  called  by  Sir  H.  Davy  alumi- 
num, I  must  declare  that  the  evidence  or  probability  of 
its  existence,  appears  to  me  much  more  feeble  even  than 
that  which  regards  the  supposed  metals  of  the  alkaline 
earths;  which  last,  in  my  judgment,  is  far  from  being 


vi  Preface. 

sufficient  to  warrant  his  arrangement  of  them  in  the 
class,  and  under  the  denomination,  of  metals. 

It  will  be  seen,  also,  that  in  the  following  pages  I  have 
not  adopted  the  name  of  chlorine^  by  which  Sir  H.  Davy 
would  distinguish  that  substance,  which  Scheele  suppos- 
ed to  be  muriatic  acid,  freed  from  hydrogene;  and  which 
Berthollet  afterwards,  with  the  general  concurrence  of 
modern  chemists,  declared  to  be  muriatic  acid,  com- 
bined with  oxygene;  whence  it  was  denominated  oxyge- 
nated muriatic  acid,  and  by  abbreviation,  oxy muriatic 
acid.  Whether  Sir  H.  Davy  be  correct  in  adopting 
Scheele's  view  of  the  nature  of  the  oxymuriatic,  and  the 
muriatic  acids,  and  in  concluding,  as  he  has  done  from 
his  own  experiments,  that  the  former  (chlorine)  is  a 
simple  or  elementary  substance,  and  that  the  latter 
"  consists  of  hydrogene  and  chlorine  in  equal  volumes;" 
or  whether  the  French  chemists,  (in  conceding  to  Davy, 
that  no  experiment  has  yet  incontestably  proved  that 
oxymuriatic  acid  gas  contains  oxygene)  are,  notwith- 
standing, justified  in  concluding,  that  the  theory  which 
admits  or  supposes  this  to  be  the  case,  is  more  natural, 
and  accords  better  with  the  whole  system  of  chemical 
facts,  than  the  opposite  theory,  is  a  question  which 
seems  to  be  yet  attended  with  doubt  and  difficulty;  and 
so  long  as  any  doubt  remains  on  this  subject,  I  think  it 
best  to  abstain  from  such  changes  of  names,  of  which 
there  have  already  been  but  too  many;  and  even  if  a 
new  name  were  expedient  for  the  oyxmuriatic  acid,  I 
should  think  that  of  chlorine,  as  a  radical^  to  have  been 
ill  chosen,  because  its  indication  of  sl  green  colour  must 
be  useless,  by  being  applicable  to  so  many  other  things, 
and  because  it  is  not  suited,  by  different  terminations, 
to  signify  those  various  combinations,  of  which  this 
acid  is  a  simple  substance,  must  be  susceptible;  a  de- 
fect, which  seems  to  have  induced  the  inventor  to  adopt 


Preface.  vir 

the  monosyllable  ane^  as  a  termination  applicable  to  its 
compounds  with  different  metals,  and  thus  to  create  the 
terms  of  argentcwe  for  horned  silver,  stannawt?  for  the 
liquor  of  Libavius,  antimoncw^  for  butter  of  antimony, 
&c.;  appellations  which  do  not  aiford  the  smallest  indi- 
cation of  the  radical  in  question,  and  which  are  com- 
pletely at  variance  with  that  nomenclature  which  Sir 
H.  Davy  has  employed  for  the  other  chemical  agents. 
To  me  it  seems,  that  if  a  new  denomination  were  re- 
quired for  the  oxymuriatic  acid  gas,  that  of  murigene, 
suggested  by  M.  Prieur,  would  be  greatly  preferable 
to  chlorine;  especially  as  it  would  harmonize  completely 
with  oxygene,  hydrogene,  nitrogene,  and  other  parts  of 
the  chemical  nomenclature;  and  by  varying  its  termina- 
tions, it  would  indicate  all  the  compounds  formed  with 
it;  e.  g.  instead  of  argentane  and  stannane,  it  would 
produce  muride  of  silver  and  muride  of  tin;  and  there 
would  be  no  incongruity  between  this  last  and  the 
muriate  of  tin,  to  which  it  would  be  convertible  by  an 
addition  of  water. 

The  volumes  herewith  offered  to  the  public,  are 
founded,  as  will  be  seen,  upon  the  results  of  a  multi- 
tude of  experiments,  made  during  the  course  of  almost 
half  a  century;  with  no  inconsiderable  expenditure  of 
money,  and  a  much  greater  one  of  time  and  of  mental 
exertion;  for  which  I  can  never  expect  any  adequate 
remuneration  or  benefit;  and,  therefore,  I  must  hope 
that  these  my  labours  may  eminently  contribute  to  ad- 
vance, not  only  the  practice  but  theory  of  the  arts  to 
which  they  relate,  as  well  as  other  branches  of  science. 
I  have  written,  indeed,  with  more  extended  views  than 
those  which  relate  merely  to  practical  dyers,  &c.  and 
have,  therefore,  often  introduced  matters,  not  of  high 
importance  to  the  latter,  though  they  could  not  have 
been  properly  omitted  in  a  work  which  professes  to 


viii  Preface* 

teach  the  philosophy  of  colours.  Should  it  ever  have 
been  matter  of  reproach  that  no  original  Work  on  this 
subject  had  appeared  in  the  English  language,  the  foun- 
dation of  that  reproach  will  be  removed  by  this  publica- 
tion, which  I  have  endeavoured  to  render  capable  of 
affording  both  entertainment  and  instruction  to  persons 
who  probably  would  not  have  been  induced  to  read  a 
more  practical  treatise  on  dyeing,  &c.;  and  that  the  many 
important  subjects  contained  in  it  may  be  rendered  as 
available  as  possible,  I  have  added  a  very  copious  gene^ 
ral  Index  to  the  second  volume. 


EXPLANATION  OP  TERMS. 


As  many  of  those,  for  whose  benefit  this  work  is  intended,  may  not  have 
been  conversant  with  the  new  Chemical  Nomenclature,  I  have  thought  it 
proper  to  insert  the  following  explanations  of  seme  of  the  terms  which  will 
occur  in  the  following  pages:  viz. 


Jlcetatea 

jicetate  of  Cofifier 

Acttate  of  Iron 

Acetic  Acid 

Acetous  Add 

Adjective  Colours^  or  Co* 
louring  Matters 

Alumina,  or  Alumine 

Ammonia 

Ainmoniates 

Arseniates 

Azote  or  Azotic  Gas 

Caloric 
Carbonates 

Carbonate  of  Lime 
Carbonate  of  Potash 

Carbonate  of  Soda 
Carbcne,  or  Carbon 

Vol.  I. 


Salts  formed  by  the  pure  acetic  acid 
with  different  bases. 

Copper  in  combination  with  acetic  acid. 

Iron  in  union  with  acetic  acid. 

Strong  dephlegmated  acid  of  vinegar. 

Undephlegmated  acid  of  vinegar. 

Those  which  acquire  their  lustre  and 
permanency  by  being  adjected  or  ap- 
plied upon  a  suitable  basis. 

The  pure  argillaceous  earth  of  alum. 

Caustic  volatile  alkali. 

Combinations  of  ammonia  with  different 
bases. 

Salts  formed  by  the  acid  of  arsenic  with 
different  bases. 

The  phlogisticated  air  of  Priestley  and 
others,  the  basis  of  nitric  acid,  and 
therefore  called  nitrogene. 

The  matter  or  cause  of  heat. 

Combinations  of  carbonic  acid  with  dif- 
ferent bases. 

Lime  united  to  carbonic  acid — Chalk. 

Fixed  vegetable  alkali  united  to  carbo- 
nic acid. 

Mineral  alkali  united  to  carbonic  acid. 

Pure  charcoal,  or  its  basis. 

b 


Explanation  of  Terms, 


Carbonic  Acid 

Citrates 

Citric  jlcid 
Fluates 

Fluoric  Acid 
Hydrogene  Gas 
Muriates 

Muriatic  Acid 

Muriate  of  Ammonia 
Muriate  of  Silver 
Muriate  of  Soda 

Muriate  of  Tin 
MuriO'Mtratea 

Murio-Sulfihates 

MuriO'Sulfihate  of  Tin 
MuriO'  Tartrites 


MuriO'Tartrite  of  Tin 

Titrates 

Nitrate  of  Alumine 
Nitrate  of  Cofifier 
Nitrate  of  Iron 
Nitrate  of  Lead 
Nitrate  of  Potash 
Nitrate  of  Silver 


Oxygene  united  to  carbone,  commonly 
called  fixed  air. 

Salts  formed  by  citric  aeid  with  diffe- 
rent bases. 

The  pure  acid  of  lemons. 

Salts  formed  by  fluoric  acid  with  diffe- 
rent bases. 

That  which  is  obtained  from  fluor  sparr 

Inflammable  air. 

Salts  formed  by  muriatic  acid  with  dif- 
ferent bases. 

The  acid  of  sea-salt,  or  common  salt — 
Marine  acid. 

Muriatic  acid  united  to  ammonia. 

Muriatic  acid  combined  with  silver. 

Muriatic  acid  united  to  soda — common 
or  sea-salt. 

Muriatic  acid  combined  with  tin. 

Salts  formed  by  muriatic  and  nitric 
acids  with  different  bases,  the  muria- 
tic being  in  the  greater  proportion. 

Salts  formed  by  muriatic  and  sulphuric 
acids  with  diff*erent  bases,  the  muria- 
tic being  in  the  greater  proportion. 

Tin  dissolved  by  muriatic  and  sulphuric 
acids. 

Salts  formed  by  muriatic  and  tartaric 
acids  with  the  difflerent  bases,  the 
muriatic  being  in  the  greater  pro- 
portion. 

Tin  dissolved  by  muriatic  and  tartaric 
acids. 

Salts  formed  by  nitric  acid  with  diffe- 
rent bases. 

Alumine  combined  with  nitric  acid. 

Copper  united  to  nitric  acid. 

Iron  in  union  with  nitric  acid. 

Lead  combined  with  nitric  acid. 

Nitre,  or  saltpetre. 

Silver  in  union  with  nitric  acid. 


Explanation  of  Terms, 


XI 


JVitric  jicid 


Mtro^ene 
J\lltrou8  jicid 


JVitrO'Muriates 

MtrO'Muriate  of  Gold 
Mtro-Muriate  of  Tin 

Oxides  (metallic') 

Oxygene 

Oxymuriatic  Acid,  or 
Chlorine  of  Davy 

Phosfihates 

Phosfihate  of  Tin 

Potass,  or  fiotash 
PriLSsic  Acid 
Prussia  tes 

Pyroligneous  Acid 

Pyrolignitea 

Soda 


Substantive  Colouring 
Matter 

Sulphates,  or  Sulfates 


Colourless  acid  of  nitre,  or  aquafortis, 
in  which  the  basis  is  saturated  with 
oxygene. 

The  basis  of  the  nitric  acid. 

Red  or  smoking  spirit  of  nitre,  in  which 
the  nitrog;ene  is  in  excess,  or  not  fully 
saturated  with  oxygene. 

Salts  formed  by  nitric  and  muriatic 
acids  with  different  bases,  the  nitric 
being  in  the  greater  proportion. 

A  solution  of  that  metal  by  nitro-muria- 
tic  acid,  formerly  called  aqua  regia. 

A  solution  of  that  metal  by  nitric  and 
muriatic  acids,  called  sjiirit,  by  scar- 
let dyers. 

Metals  in  union  with  oxygene,  former- 
ly called  calces. 

The  basis  of  pure  or  vital  air,  or  the 
aerial  acidifying  principle. 

The  dephlogisticated  marine  (or  mu- 
riatic) acid  of  Sc^ieele,  supposed  by 
Berthollet  to  be  muriatic  acid  com- 
bined with  oxygene- 

Salts  formed  by  phosphoric  acid  with 
different  bases. 

A  combination  of  that  metal  with  phos- 
phoric acid. 

Caustic  vegetable  alkali. 

The  colouring  matter  of  Prussian  blue. 

Combinations  of  the  Prussian  colouring 
matter  with  different  bases. 

The  empyreumatic  acid  obtained  by 
distillation  from  wood,  &c. 

Combinations  of  the  pyroligneous  acid 
with  different  bases. 

One  of  the  fixed  alkalies  in  a  caustic 
state— the  basis  of  common  or  sea- 
salt. 

That  which  requires  ri  bso  on  samor- 
dant  to  give  it  lustre  and  permanency. 

Salts  formed  by  sulphuric,  or  sulfuric, 
acid  with  different  bases. 


Xll 


Explanation  of  Terms, 


Sulphate  of  Alumine 
Sulfihate  of  Copfier  ~ 

Sulfihate  of  Indigo 
Sulfihate  of  Iron 

Sulfihate  of  Zinc 

Sulfihure,  or  Sulfihuret  of 
jlntimony 

Tannin 

Tartritea 

Tar  trite  of  Alumine 

Tartrite  qf  Tin 


Common  alum. 

A  combination  of  that  metal  with  sul- 
phuric acid — blue  vitriol. 

A  solution  of  indigo  by  sulphuric  acid, 

A  combination  of  that  metal  with  iron, 
called  green  vitriol  or  copperas. 

A  combination  of  zinc  with  sulphuric 
acid. 

A  combination  of  that  metal  with  sul- 
phur— crude  antimony. 

Vegetable   matter  by  which  skins  are 
tanned  or  changed  to  leather. 

Combinations  of  tartaric  acid  with  diffe- 
rent bases. 

Tartaric  acid  united  to  the  earth  of 

alum. 
Tartaric  acid  in  union  with  tin» 


INTRODUCTION, 


COXCIBXING  THE 


ORIGIN  AND  PROGRESS 


DYEING  AND  CALICO-PRINTING, 


The  Great  Author  of  Nature  having  allotted  and  em- 
ployed colours,  to  distinguish  and  adorn  the  various 
productions  of  his  power,  wisdom,  and  goodness,  has 
also  endowed  some  animals,  and  particularly  man,  not 
only  with  perceptions  of  the  differences  of  colours,  but 
also  of  the  beauty  arising  from  them,  and  their  various 
combinations:  and,  in  consequence  of  these  perceptions, 
mankind,  even  in  the  rudest  states  of  human  existence, 
have  been  disposed  to  admire  and  desire  ornaments,  de- 
pending on  gaudy  and  varied  colours;  which,  in  the 
state  of  naked  savages,  they  have  generally  applied  to 
their  skins,  and  afterwards  to  their  garments,  when 
they  had  approached  so  far  towards  civilization,  as  to 
manufacture  and  wear  clothing.^  From  these  motives, 

*  A  confirmation  of  this  observation  may  be  found  in  the  1  st 
chapter  of  the  22d  book  of  Pliny's  Natural  History,  in  these  words: 
«  Equidem  et  formae  gratia  ritusque  perpetui,  in  corporibus  suis 
aliquas  exterarum  gentium  uti  herbis  quibusdam,  adverto  animum. 
Illiunt  certe  aliis  aliae  faciem  in  populis  barbarorum  foeminse  ma- 
resque  etiam  apud  Dacos  et  Sarmatas  corpora  sua  inscribunt. 
Simile  plantagini  glastum  in  Gallia  vocatur;  quo  Brittanorum  con- 
juges  narusque  toto  corpore  oblite;  quibusdam  in  sacris  et  nudce 
incedunt,  iSthiopum  colorem  imitantes." 


xiv  Introduction, 

and  the  rude  trials  induced  by  them,  even  in  remote 
ages,  the  arts  of  dyeing  and  calico-printing  undoubtedly 
ori,s:inated. 

It  will  appear  in  the  following  chapters,  that  colour- 
ing matters  are  of  two  very  distinct  classes;  one,  which 
requires  no  basis,  or  mediating  substance,  to  fix  it  upon 
other  objects,  and  which  I  have,  therefore,  denominated 
substantive  colouring  matter;  and  the  other,  whose  du- 
rability* depends  chiefly,  if  not  exclusively,  upon  the 
interposition  of  some  basis,  and  which,  for  that  reason, 
I  have  called  adjective  colouring  matter;  and  as  dyes  of 
the  latter  class,  by  being  the  most  numerous,  would 
naturally  present  themselves  in  the  greatest  abundance, 
and  be  applied  without  any  means  to  render  them  per- 
manent, (because  it  would  require  numerous  trials,  and 
a  concurrence  of  many  fortunate  accidents,  to  discover 
the  use  of  any  such  basis)  we  may  reasonably  conclude, 
that  most  of  the  stains  or  colours  first  applied  to  wool, 
linen,  or  cotton,  would  have  been  fugitive.  This,  doubt- 
less, was  true  of  those  which  the  Gauls  are  said  by 
Pliny  to  have  dyed  from  herbs; f  as  it  has  been  of  those 

*  This  is  not  always  completely  true  in  regard  to  ivool^  which  is 
capable  of  attracting  some  few  of  the  adjective  colouring  matters, 
particularly  those  of  madder,  galium,  and  cochineal,  so  as  thereby 
to  acquire  tints  of  some  durability,  unassisted  by  any  basis;  but  the 
colours  so  obtained  will  be  much  less  durable,  and  much  more  de- 
ficient in  brightness,  than  they  would  have  if  dyed  upon  a  suitable 
basis.  But,  in  regard  to  linen  or  cotton,  it  may  be  observed,  that 
they  have  no  such  attraction  for  adjective  colouring  matters,  and 
are,  therefore,  incapable  of  being  dyed  by  them,  without  the  aid  of 
a  basis. 

t "  Transalpina  Gallia  herbis  Tyrium  atque  conchylium  tingit, 
omneisque  alios  colores:  nee  querit  in  profundis  murices,  seseque 
objiciendo  escam,  dum  praeripit,  belluis  marinis,  intacta  etiam 
ancoris  scrutatur  vada,  ut  inveniat  per  quod  facilius  matrona  adul- 
tero  placeat,  corruptor  insidietor  nuptae."  Lib.  xxii.  c.  2. 

Hero- 


Introduction,  xv 

which,  in  later  times,  have  been  seen  among  the  un- 
civilized inhabitants  of  recently  discovered  islands  and 
countries:  and  we  may,  therefore,  consider  tl^e  disco- 
very of  these  bases,  (denominated  mordants  by  the 
French)  and  especially  that  of  alum,  (which  is  of  all 
others  the  most  generally  useful  in  fixing  adjective  co- 
louring matters,)  as  being  a  most  important  event  in 
the  history  of  dyeing;  though  it  is  now  impossible  to 
ascertain  either  the  time  or  place  at  which  this  disco- 
very was  made. 

Beckman,  in  the  Gottingen  Memoires,  and  more  re- 
cently in  the  first  volume  of  his  History  of  Inventions, 
has  endeavoured  to  maintain,  that  the  alum  of  the  an- 
cients, was  not^  like  that  of  the  moderns,  a  combination 
of  sulphuric  (or  vitriolic)  acid,  with  that  white  argilla- 
ceous earth,  now  called  alumine^"^  (or  alumina,)  but  a 
combination  of  that  acid  with  either  iron  or  copper,  or 
perhaps  zinc,  and  constituting  those  substances  which 
were  afterwards,  and,  until  very  lately,  called  green, 
blue,  and  white  vitriols;^  and  in  support  of  this  his 

Herodotus,  indeed,  as  an  extraordinary  fact,  mentions  a  people 
living  on  tlie  borders  of  the  Caspian  sea,  who,  by  bruising  the 
leaves  of  a  particular  tree,  and  mixing  them  vf'nh  water,  obtained 
a  colour,  by  which  they  afterwards  painted  upon  their  garments 
the  figures  of  animals,  &c.;  which  figures  water  could  not  after- 
wards remove.  Book  Clio,  c.  c.  iii. 

*  This  is  not  a  complete  description  of  alum,  which,  in  fact,  is  a 
trijile  salt,  (as  seems  to  have  been  first  discovered  by  Margraaff,) 
for  the  combination  of  sulphuric  acid  with  alumine  will  not  crys- 
tallize, without  an  addition  of  either  potash  or  ammonia.  Accord- 
ing to  Vauquclin,  100  grainsofalum  consist  of  30.52  of  acid,  10.50 
of  alumine,  10.40  of  potash,  and  48.58  of  water. 

t  When  the  term  of  vitriol  was  first  used  is  not  known.  Beck- 
man  could  find  it  in  no  writer  older  than  Albertus  Magnus,  who 
says,  "  Viride  etiam  quod  a  quibusdam  vitreo  leum  vocatur." 
Agricola  and  Vossius  conjecture,  that  it  was  suggested  by  the 


xvi  Introduction. 

opinion,  he  alleges,  that  the  Greek  and  Roman  authors, 
particularly  Dioscorides  and  Pliny,  mention  no  other 
than  native  alum,  as  being  then  known;  that  alum  crys- 
tallized like  the  modern,  is  but  seldom  produced  spon- 
taneously; and  that  no  mention  can  be  found  in  any- 
ancient  writer,  of  the  existence  of  any  alum  work,  ex- 
cepting that  in  Spain,  noticed  by  Pliny,  and  which  had 
for  its  object  the  crystallization  of  a  sulphate  of  either 
copper  or  iron.  He  alleges,  moreover,  that  every  thing 
stated  by  ancient  writers  concerning  their  alum,  is  ap- 
plicable to  the  metallic  sulphates,  since  called  vitriols. 
But  this  last  allegation  at  least,  is  not  correct,  as  may- 
be seen  by  recurrii.g  to  Pliny's  35th  book,  chap.  xv. 
intitled,  *'  De  sulphure,  alumine^^  et  generibus  corum, 
&c."  in  which  he  says,  there  are  many  kinds  of  alum: 
"  Plura  et  ejus  genera:"  that  of  these,  the  island  of  Cy- 
prus affords  two;  one  white,  and  the  other  black;  and 
that  though  their  colours  do  not  differ  so  much,  their 
uses  are  very  opposite;  the  white  alum  being  of  the 
greatest  utility  for  dyeing  upon  wool,  clear  and  light,  or 
bright,  colours;  as,  on  the  contrary,  the  black  is,  for 
dyeing  brown  and  dark  colours:  "  in  Cypro  candidum  et 
nigrum,  exigua  coloris  differentia,  cum  sit  usus  magna; 
quoniam  inficiendis  claro  colore  lanis  candidum  iiqui- 


likeness  of  these  crystallized  sulphates  to  §;lass;  to  which,  indeed, 
Pliny  had  long;  before  compared  them,  in  the  1 2th  chapter  of  his 
34th  book;  where,  after  having  described  the  manner  in  which 
the  atramentum  sutorium,  (sulphate  of  iron,)  was  made  to  crystal- 
lize upon  ropes  suspended  over  water,  which  held  iron  in  solution, 
so  that  one  end  of  each  was  immersed  therein,  he  says,  "  vitrnm- 
que  esse  creditur." 

*  Beckman  supposes  that,  excepting  Columella,  Pliny  is  the 
oldest  writer,  in  whose  works  the  term  alumen  ha*  been  found) 
and  that  its  derivation  is  unknown.  He  then  asks,  whether  it  may 
not  have  come  from  Egypt,  with  the  6esr  sort  of  alum? 


Introduction,  xvii 

dum,  que  utilissimum  est,  contraque  fuscis  aut  obscuris 
nigrum."  He  adds,  that  they  were  all  obtained  by  na- 
tural exudations  from  the  earth;  in  Spain,  Egypt,  Ar- 
menia, Macedonia,  Pontus,  and  Africa;  and'  in  the 
islands  of  Sardinia,  Melos,  Lipara,  and  Strongyle;  and 
that  of  all  these  the  best  simply  is  that  which  comes 
from  Egypt,  and  next  to  this,  that  of  Melos.  He  after- 
wards proceeds  to  notice,  separately,  five  several  sorts, 
mentioning  the  Greek  names  of  four  of  them,  viz.  phor- 
mion,  paraphoron,  schistos,  (called  also  trichitis  and 
chalcitis,)  and  strongyle.  His  last  or  fifth  species  was  in 
great  estimation,  and  called  melmum,  because  it  came 
from  the  island  of  Melos;  and  he  finally  observes,  that 
the  different  kinds  of  alum  were  all  possessed  of  an 
astringent  property,  which  had  obtained  for  them  their 
common  Greek  appellation,  (fuTrryj^za.) 

That  some  of  the  several  matters  here  mentioned  by 
Pliny,  under  the  general  name  of  alum,  consisted  prin^ 
cipally  of  iron,  must  be  admitted:  because,  in  addition 
to  other  reasons,  he  intimates  that  two  of  them  pro- 
duced a  black  colour  with  galls,  and  the  peels  of  the 
pomegranate;  and  there  are  grounds  also  for  believing, 
that  one  of  them  was  a  sulphate  of  copper.  But  I  can 
discover  no  sufficient  reason  in  this,  or  in  any  other  part 
of  his  work,  for  believing,  that  Pliny  did  not  also,  un- 
der the  name  of  alum,  include  a  sulphate  of  alumine^ 
not,  perhaps,  crystallized  like  our  alum;^*  but  in  such  a 

*  According  to  Berthollet,  there  is  a  mine  of  alum  at  Solfataraj 
near  Naples,  which,  in  the  form  of  a  white  earth,  contains  alum, 
formed  by  the  action  of  the  sulphureous  acid  disengaged  by  the 
heal  of  the  volcano,  upon  the  argillaceous  matter  evolved  by  it. 
There,  the  alum  requires  only  to  be  dissolved  and  crystallized. 
From  a  mine  like  this,  or  its  earth,  the  good  effects  which  Pliny 
ascribes  to  the  white  alum  of  Cyprus  might  be  readily  obtained. 
The  famous  alum  mines  of  Tolfa,  near  Civita-Veehia,  are  still 

Vol.  I.  c 


xviii  Introduction, 

state  of  purity,  especially  in  regard  to  iron,  as  would 
enable  it  to  produce  the  clear  and  lively  colours  for 
which  Pliny  states  one  of  his  alums  to  have  been  high- 
ly useful;  and  which  the  sulphates  of  iron  and  copper, 
would  not  have  produced;  nor  that  of  zinc,  (were  it 
even  certain  that  the  ancients  had  ever  employed  it  for 
dyeing,)  unless,  (which  is  not  credible,)  they  possessed 
it  in  a  state  of  much  greater  exemption  from  iron,  than 
we  find  it  even  at  this  time. 

The  single  fact  of  their  (I  mean  the  Greeks  and  Ro- 
mans) having  been  able,  long  before  Pliny  wrote,  to 
dye  from  the  kermes,  that  beautiful  red,  or  coccinean 
colour,  which  afterwards  took  the  name  of  scarlet,  and 
obtained  the  highest  degree  of  estimation,  is  alone  suf- 
ficient to  prove  that  they  must  have  possessed  alum  in 
some  degree  of  purity  at  least,  since  it  is  known  and 
admitted  that  for  dyeing,  they  were  wholly  ignorant  of 
the  use  of  tin,  the  only  other  basis  by  which  the  colour 
in  question  could  have  been  produced.  Indeed,  the 
kermes  would  have  afforded  nothing  but  a  black  dye 
with  any  preparation  of  iron;  and  nothing  better  than  a 
dark  brown  with  any  preparation  of  copper. 

Beckman  says,  (vol.  i.  p.  292  of  his  History 'of  In- 
ventions, translated  by  Johnston,)  that  "  when  our  alum 
became  known,  it  was  considered  as  a  species  of  the 
ancient;  and  as  it  was  purer,  and  more  proper  to  be 
used  on  most  occasions,  the  name  of  alum  was  soon 
appropriated  to  it  alone.  The  kinds  of  alum,  however, 
known  to  the  ancients,  which  were  real  vitriols,  main- 
tained a  preference  in  medicine,  and  for  dyeing  black .^"^ 
But  much  of  this  appears  to  me  absolutely  incredible, 

purer,  according  to  th»  accounts  of  Monnet,  Bergman,  and  Vau- 
quelin,  by  each  of  whom  they  were  analysed;  but  there  the  mineral 
requires  torrefaction. 


Introduction^  xix 

as  persons  who  had  been  acquainted  with  the  alum  of 
the  ancients,  would  not,  when  that  of  the  moderns  was 
made  known  to  them,  have  considered  it  as  a  species 
of  the  ancient,  unless  there  had  been  some  cause  for 
doing  so;   and  they  never  could  have  supposed  th^t 
there  was  cause  to  consider  our  sulphate  of  alumine 
as  a  -species  of  the  ancient  alum,  if  the  latter  had  been 
so  peculiarly  deserving  of  estimation  for  dyeing  black; 
or  if,  at  least,  one  kind  of  it  had  not  been  suited  to  dye 
the  very  different  colours  which  the  sulphate  of  alumine 
is  alone  able  to  produce.  To  the  dyer,  no  two  sub- 
stances could  have  appeared  so  opposite  or  dissimilar; 
and  there  were,  therefore,  no  two  substances  which  he 
would  be  so  little  disposed  to  confound;  and  to  con- 
found in  a  manner  so  extraordinary,  as  that  of  giving 
the  old  name  of  alum  exclusively  to  a  sypjx>sed  new 
and  very  different  substance.^  and  inventing  a  new  name 
(that  of  vitriol)  for  the  metallic  sulphates,   which  he 
(Beckman)  supposes  to  have  before  exclusively  borne 
the  name  of  alum.   There  was  theUy  nothing  in  tlie 
name  which  could  afford  any  motive  for  this  change,  if 
we  suppose,'  with  him,  that  it  had  for  so  many  ages 
been  appropriated  exclusively  to  the  sulphates  of  iron, 
copper  and  zinc;  and  it  would  in  that  case  have  been 
much  more  natural  and  convenient,  to  have  allowed  the 
latter  to  retain  the  name  by  which  they  had  been  so 
long  distinguished,  and  to  have  invented  a  new  name 
for  the  supposed  new  production.  The  truth  seems  to 
be  that,  notwithstanding  the  ignorance  of  the  barbarous 
ages,  the  inconvenience  of  calling  substances,  possessing 
the  most  opposite  properties,  by  one  common  name, 
had  been  generally  felt;  and  that  to  obviate  this  inconve- 
nience, the  name  vitriol,  as  distinguishing  the  metallic 
sulphates,  had  been  gradually  adopted,  and  that  of  alum 
had  been  appropriated  exclusively  to  the  (perhaps  im^ 


UK  Introduction, 

pure)  sulphate  of  alumine;  and  that  when  this  came  to 
be  introduced  from  Syria  in  a  crystallized  form,  it  ob- 
tained in  Italy,  (for  reasons  to  be  hereafter  considered,) 
the  additional  appellation  of  rocca,  or  roccha,  to  distin- 
guish ii  from  that  which  had  before  been  in  common 
use;  and  hence  the  French  name  of  alun  de  roche,  and 
the  English  of  rock,  or  roach  alum. 

Were  it  ascertained  that  the  Greeks  and  Romans,  at 
the  times  of  Dioscorides  and  Pliny,  were  wholly  unac- 
quainted with  crystallized  sulphate  of  alumine,  even  Ih 
that  which  Beckman  calls  the  best  sort,  brought  from 
Egypt,  I  should  think  it  highly  probable,  notwithstand- 
ing, that  such  alum  existed,  and  was  then  employed, 
among  the  people  of  Hindostan  and  other  parts  of  India; 
where,  (as  will  appear  by  facts  stated  between  pages 
257  and  260  of  this  volume,)  the  arts  of  dyeing  and 
calico  printing  had  been  practised  more  than  two  thou- 
sand years  ago,  exactly  in  the  same  manner,  and  with 
the  very  same  means,  (particularly  crystallized  alum 
and  acetate  of  iron,)  which  were  found  to  be  in  com- 
mon  use  among  them,  when  the  Portugueze  first  reach- 
ed that  part  of  Asia,  by  sailing  round  the  Cape  of  Good 
Hope;  and  without  which,  the  art  of  calico  printing 
could  never  have  existed.  It  will  also  appear,  that  tl>e 
Egyptians,  before  the  time  of  Pliny,  had  practised  this 
art  of  calico  printing,  and  had  borrowed  therewith  some 
productions  necessary  for  the  exercise  of  it,  from  Hin- 
dostan;* and  it  may  be  presumed,  that  crystallized  alum, 

*  Among  these,  (as  is  proved  at  p.  186,  &c.  of  this  volume,)  v^as 
that  most  wonderful  production,  indigo^  which  seems  to  have  origi- 
nated among  the  Hindoos.  The  people  of  other  countries  had,  in- 
deed, found  out  ways  to  communicate  substantive  blue  colours  from 
different  plants,  and  particularly  from  woad,  or  the  isatis  tinctoria, 
Linn.,  but  not  to  precipitate  and  collect  the  colouring  matter  in  a 
4ry  solid  form,  like  indigo.  T/iia  the  people  of  Hindostan  hai  not 


Introduction,  xxi. 

which  is  even  now  sometimes  imported  from  India  to 
this  country,  (and  which  has  been  in  use  there  during 
30  many  centuries,  that  no  means  exist  for  ascertaining 
when  its  use  began,)  would,  from  its  indispensable  ne- 
cessity, have  been  carried  thence  with  other  dyeing 
drugs  to  Egypt;  and  to  me  it  certainly  does  not  seem 
improbable,  that  this  was  that  sort  of  Egyptian  alum, 
which  Pliny  mentions  as  being  in  greater  estimation 
than  any  other.  Beckman,  indeed,  says,  p.  291,  "  It  is 
well  known  that  real  alum  is  reckoned  among  the  ex- 
ports of  Egypt  at  present;  but,  (he  adds,)  I  am  ac- 
quainted with  no  author  who  mentions  the  place  where 
it  is  found  or  made,  or  who  has  described  the  method 
of  preparing  it."  Whether  the  Egyptians,  after  obtain- 
only  effected,  but  they  had  afterwards  done  t/iat  which  must  have 
been  more  difficult;  they  had  discovered  the  means  of  dissolving 
indigo  when  so  prepared,  in  ways  the  most  suitable  for  applying 
and  fixing  its  colour  permanently  on  the  substances  to  be  dyed  with 
it;  which  the  Greeks  and  Romans  do  not  appear  to  have  ever  per- 
formed, though  they  knew  how  to  powder  indigo,  and  apply  it  as  a 
paint. 

From  the  fifth  volume  of  that  extensive  work,  entitled,  "  Me- 
moires  concernants  I'Histoire,  les  Sciences,  les- Arts,  les  Moeurs, 
&c.  des  Chinois,'*  it  appears  that  wool  was  never  worn  in  China 
but  as  a  substitute  for  fur,  and  that  cotton  and  silk,  being  the  only 
substances  ever  dyed  by  the  inhabitants,  received  all  their  colours 
from  vegetable  tingcnt  matters;  that  these  colours  were  principally 
red,  blue,  violet,  and  what  is  called  a  woad  colour;  and  that,  under 
the  three  first  dynasties,  the  business  of  dyeing  was  chiefly  prac- 
tised by  the  female  part  of  each  family,  for  its  own  particular  use: 
and  it,  probably,  continued  to  be  practised  without  any  thing  like 
principle  or  science  until  near  the  end  of  the  seventh  century, 
when  the  Chinese,  discarding  their  own,  borrowed  the  arts  and 
means  of  dyeing  which  were  then  in  use  among  the  Indians  and 
Persians:  and  it  is  said,  that  alum  and  copperas,  which  the  Chinese 
did  not  use  before,  were  among  the  means  so  borrowed;  a  fact 
which  renders  it  probable  that  there  was  little,  if  any  thing,  in  the 
Chinese  art  of  dyeing,  of  which  the  loss  need  now  be  regretted. 


xxii  Lit  roduct  1071, 

ing  alum  from  India,  had,  by  doing  so,  discovefed  the 
means  of  preparing  it  in  their  own  country;  or  whether 
they  continued  to  obtain  it  from  India,  or  were  after- 
wards supphed  with  it  by  the  inhabitants  of  any  of  the 
intermediate  countries,  who  might  have  acquired  this 
knowledge  from  the  Hindoos,  I  know  not;  but  it  seems 
evident  that  Egyptian  alum,  however  it  may  have  been 
obtained,  had  been  long  and  far  famed,  since  Herodotus 
(in  a  passage  which  Beckman  has  quoted  from  his  se- 
cond book,  c.  180.)  relates,  that  when  the  people  of 
Delphos  solicited  a  contribution  for  re- building  their 
temple,  which  had  been  burnt,  Amasis,  king  of  Egypt, 
sent  them  a  thousand  talents  oi  alum, 

Beckman  supposes  that  crystallized  sulphate  of  alu- 
mine,  similar  to  our  alum,  was,  undoubtedly,  first  made 
in  the  East;  and  that  it  was  not  known  in  Europe  be- 
fore the  end  of  the  twelfth  century;  and  if  this  be  true, 
it  seems  probable  that  the  knowledge  of  it,  and  of  the 
methods  of  bringing  it  into  a  crystallized  form,  had 
gradually  spread  from  Hindostan,  through  Persia,  and 
the  intermediate  countries,  to  Syria,  where  it  was  made 
"use  of  before  the  overthrow  of  the  Greek  empire;  and 
whence  it  was  confessedly  brought  to  Italy  in  the  four- 
teenth century.*  Beckman  has  given  us  extracts  from 
the  writings  of  three  respectable  historians,  viz.  John 
Jovianus  Pontanus,  Peter  Bizaro,  and  Augustin  Justi- 
nian, who  all  relate,  that  about  the  year  1460,  Bartho- 
lomew Perdix,  (by  some  called  Pernix,)  a  Genoese 

"*  Beckman  mentions  alum  works  as  existing  near  to  Constanti- 
nople, in  the  fifteenth  century;  and  also  one  of  great  celebrity  in 
the  neighbourhood  of  Smyrna;  whence  the  Italians  procured  alum 
and  other  dyeing  drugs.  He  also  mentions  an  Italian  treatise  writ- 
ten by  Francisco  Balducci,  about  the  middle  of  the  fourteenth  cen- 
tury, by  which  it  appears  that  the  Italians  were  then  acquainted 
with  no  other  than  Turkish  alirm. 


Introduction.  xxiii 

merchant,  who  had  become  acquainted  with  the  prepa- 
ration of  alum  in  Syria,  when  returning  thence  to  Italy, 
happened,  at  the  island  of  iEnaria,  now  called  Ischia, 
or  Hiscla,  to  observe  large  alum  stones  among  the  sub- 
stances which  had  been  thrown  up,  more  than  one  hun- 
dred years  before,  in  consequence  of  the  eruption  of  a 
destructive  volcano  there;  and  that,  having  calcined 
some  of  these  stones  in  a  furnace,  he  extracted  from 
them  excellent  alum.  But  these  historians  all  assert, 
contrary  to  the  supposition  of  Beckman,  that  he,  (Per- 
dix,)  in  doing  this,  only  revived  and  brought  back  to 
Italy  an  art  which  had,  with  many  others,  been  lost 
amidst  the  darkness  which,  during  several  centuries, 
prevailed  over  the  western  empire;  which  art  he  had 
himself  learned  at  the  city  of  Rocca,  in  Syria.  Beckman 
says,  he  had  at  first  supposed,  that  this  city  might  have 
been  Rocca,  on  the  Euphrates;  but  he  had  afterwards 
thought  it  more  likely  to  have  been  Edessa,  sometimes 
called  Rocha,  &c.,  and  also  Roccha;  and  that,  though 
the  latter  is  considered  as  being  in  Mesopotamia,  the 
Supposed  limits  of  Syria  might,  at  that  time,  h^ve  ex- 
tended thus  far.  From  this  city  of  Rocca,  Beckman 
supposes,  with  Lisbnitz  and  others,  that  the  best  crys- 
tallized alum  obtained  in  Italy  the  additional  epithet  of 
Rocca;  while  some  persons,  and  among  them  Julius 
Cassar  Scaliger,*  think  it  to  have  been  derived  from: 
the  Greek  name  of  a  rock,  alum  being  obtained,  by 
boiling,  from  stones;  and  it  seems  to  have  been  this 
opinion  which  caused  the  appellation  to  be  translated 
into  Latin,  by  the  words  alumen  rupeum,  and  into 
French  by  those  of  alum  de  Roche;  and  there  are  again 

*  "  Vulgo  audis  alumen  rocha^  que  Grseca  vox  maximal  Europst 
servit  parti  ad  rupem  significandum."  Exotic.  Exercitat.  Francf. 
i^l2»8vo.p.  325. 


xxiv  Introduction, 

some,  who  imagine,  that  this  name  was  suggested,  and 
occasioned  more  immediately,  by  the  alum  rocks  of  the 
famous  mines  at  Tolfcy  near  Civita-Vechia,  from  which 
alum  of  the  purest  quality  has  been  longer  extract- 
ed than  from  any  other  mine  now  subsisting  in  Eu- 
rope; and  these  were  discovered  by  John  de  Castro,  a 
few  years  after  Perdix  had  begun  to  produce  alum 
from  the  stones  which  he  found  at  Ischia.  Of  this 
memorable  discovery,  which  happened  during  the  pon- 
tificate of  Pius  the  Second,  that  pope  has  given  a  cir- 
cumstantial account;  for  which  see  *'  Pii  Secundi  Com- 
ment, refum  memorab.  quje  temp,  suis  contingerunt," 
h.z.  Francofurti,  1614,  fol.  p.  185.^ 

*  Beckman  has  extracted  this  account,  of  which  the  following 
are  the  principal  parts,  viz. 

This  John  cle  Castro,  *'  being  fond  of  travelling,  had  resided  some 
ftime  at  Constantinople,  and  acquired  much  wealth  by  dyeing  cloth 
made  in  Italy,  which  was  transported  thither,  and  committed  to 
his  care,  on  account  of  the  abundance  of  alum  in  that  neighbour- 
hood. Having  by  these  means  an  opportunity  of  seeing  daily  the 
manner  in  which  alum  was  made,  and  from  what  stones,  or  earth, 
it  was  extracted,  he  soon  learned  the  art.  When,  by  the  will  of 
God,  that  city  was  taken  and  plundered,  about  the  year  1455,  by 
Mahomet  II.,  Emperor  of  the  Turks,  he  lost  his  whole  property; 
but,  happy  to  have  escaped  the  sword  of  these  cruel  people,  he  re- 
n;urned  to  Italy,  after  the  assumption  of  Pius  II.,  to  whom  he  was 
related,  and  from  whom  he  obtained,  as  an  indemnification  for  his 
losses,  the  office  of  commissary-general  over  all  the  revenues  of 
Ihe  Apostolic  Chamber,  both  within  and  without  the  city.  While 
iin  this  situation,  he  was  traversing  all  the  hills  and  mountains, 
searching  the  bowels  of  the  earth;  he  at  length  found  some  alum 
atones  in  the  neighbourhood  of  Tolfa;  and  having  made  experi- 
ments by  calcining  them,  he  obtained  alum:  and  repairing  to  the 
P'ontiff,  said  to  him,  "  I  announce  to  you  a  victory  over  the  Turk. 
H(e  draws  yearly  from  the  Christians  above  three  hundred  thou- 
sand pieces  of  gold,  paid  to  him  for  the  alum  with  which  we  dye 
W  ool  of  different  colours,  because  none  is  found  here,  but  a  little  at 
tllie  island  of  Hiscla,  formerly  called  ^naria,  near  Puteoli,  and  in 
tjie  cave  of  Vulcan  at  Lipari,  which  having  been  exhausted  by  the 


Introduction*  xxy 

The  wealth  which  the  pope  obtained  from  the  disco- 
Very  and  working  of  the  mines  at  Tolfa,  encouraged 
and  produced  similar  undertakings  in  other  parts  of 

Romans,  is  now  almost  destitute  of  that  substance.  I  have,  how- 
ever, found  seven  hills,  so  abundant  in  it,  that  they  would  be 
almost  sufficient  to  supply  seven  worlds.  If  you  will  send  for 
workmen  sufficient,  and  cause  furnaces  to  be  constructed,  and  the 
stones  to  be  calcined,  you  may  furnish  alum  to  all  Europe;  and 
that  gain  which  the  Turks  used  to  acquire  by  this  article,  being 
thrown  into  your  hands,  will  be  to  him  a  double  loss.  Sec'  These 
words  of  Castro  appeared  to  the  pontiff  as  the  mere  result  of  idle 
dreams.  He,  however,  employed  skilful  people,  who  found  that  the 
stones  really  contained  alum;  but  least  some  deception  might  have 
been  practised,  others  were  sent  to  the  place  where  they  bad  been 
found,  who  met  with  abundance  of  the  like  kind.  Artists,  who 
had  been  employed  in  the  Turkish  mines  in  Asia,  were  then 
brought  from  Cenoa;  and  these,  having  closely  examined  the  na- 
ture of  the  place,  declared  it  to  be  similar  to  that  of  the  Asiatic 
mountains  which  produce  alum;  and,  shedding  tears  for  jov,  they 
kneeled  down  three  times,  worshipping  God,  and  praising  his  kind- 
ness in  conferring  so  valuable  a  gift  on  our  age.  The  stones  were 
calcined,  and  produced  alum  more  beautiful  than  that  of  Asia^  and 
superior  in  quality.*  Some  of  it  was  sent  to  Venice  and  to  Flo- 
rence; and  being  tried,  was  found  to  answer  beyond  expectation. 
The  Genoese  first  purchased  a  quantity  of  it,  to  the  amount  of 
twenty  thousand  pieces  of  gold;  and  Cosmo,  of  Medicis,  for  this 
article,  laid  out  afterwards  seventy-five  thousand.  On  account  of 
this  service,  Pius  thought  Castro  worthy  of  the  highest  honours, 
and  of  a  statue,  which  was  erected  to  him  in  his  own  country,  with 
this  inscription: — *  To  John  di  Castro,  the  inventor  of  alum;'  and 
he  received,  besides,  a  certain  share  of  the  profit;  immunities  and 
a  share  also  of  the  gain,  were  granted  to  the  two  brothers,  lords  of 
Tolfa,  in  whose  land  the  aluminous  mineral  had  been  found.  This 
accession  of  wealth  to  the  church  of  Rome  was  made,  by  the  divine 

•  This  alum  continues  to  be  known  under  the  name  of  Roman  alum,  and 
esteemed  above  all  others;  principally  because  it  contains  but  about  half  as 
much  iron  as  most  other  alums:  the  latter,  however,  may  be  rendered  equal- 
ly pure  and  valuable,  by  calcining,  then  dissolving,  and  afterwards  re-crystal, 
lizing  them.  Stahl,  Newman,  Pott,  and  other  eminent  chemists,  considered 
ahimine  as  a  calcareous  earth,  and  not  as  being  an  earth,  which  it  is,  iui^c^ 
neris,  nearly  related  to  clay,  but  diftering  from  it. 

Vol,  I.  d 


xxvi  Introduction, 

Italy,  particularly  at  Volterra,  in  the  district  of  Pisa, 
though  their  success  was  greatly  obstructed  by  the  ob- 
stacles which  the  pope  contrived  and  employed  against 
them,  in  order  that  he  might  monopolize  all  the  benefits 
to  be  derived  from  the  manufacture  and  sale  of  alum;  of 
which  he  raised  the  price  so  exorbitantly,  that  alum  pro- 
cured from  the  Turks  was  found  much  cheaper  than 
that  of  Tolfa,  and,  therefore,  employed.  But  to  obviate 
this  interference,  the  pope  pretended  to  devote  the  re- 
venue produced  by  his  alum  works  to  the  defence  of 
Christianity  against  the  Turks,  and  menaced  all,  who 
should  act  so  unchristianly,  as  to  purchase,  or  procure, 
alum  from  these  infidels,  with  excommunication;  which 
prohibitions  were  renewed  by  several  of  his  successors. 

It  appears  from  Biringocci's  Pyrotechn,  p.  31,  that 
the  first  alum  work  established  out  of  Italy,  subsequent- 
ly to  the  discovery  of  those  of  Tolfa,  was  that  of  Alma- 
caron,  near  Carthagena,  in  Spain;  whence,  as  is  stated  in 
Guicardini's  description  of  the  Netherlands,  large  quan- 
tities of  alum  were  brought  to  Antwerp,  in  the  early 
part  of  the  sixteenth  century. 

In  England  the  first  alum  work  was  that  of  Gisbo- 
rough,  in  Yorkshire,  begun  near  the  end  of  Queen  Eli- 
zabeth's reign,  upon  lands  belonging  to  Sir  Thomas 
Chaloner,  who  secretly  procured  workmen  from  the 
alum  works  at  Tolfa,  no  person  in  England  then  know- 
ing how  to  produce  it.  This  seduction  of  his  workmen 
so  enraged  the  pope,  as  we  are  told  by  Pennant,  in  his 
Tour  to  Scotland,  that  his  holiness  endeavoured  to 
frighten  and  recall  them  by  curses,  or  anathemas,  in 
the  very  form  left  us  by  Ernulphus. 

blessing,  under  the  pontificate  of  Pius  II.;  and  if  it  escape,  as  it 
ought,  the  hands  of  tyrants,  and  be  prudently  managed,  it  may  in- 
crease; and  afford  no  small  assistance  to  the  Roman  pontiffs,  in 
supporting  the  burthens  of  the  Christian  religion.** 


Introduction^  xxvii 

The  intimate  and  important  connection  of  the  history 
of  alum  with  that  of  dyeing,  has  induced  me  to  state 
these  facts,  which  I  have  chiefly  derived  from  Beck- 
man's  first  volume;  though  I  have  not  thought  it  right 
to  adopt  soiiie  of  his  conclusions  on  this  subject. 

To  discover  by  retrospection  all  the  ways  and  means 
by  which  an  art  like  that  of  dyeing  has  been  improved 
from  its  earliest  and  most  simple  beginnings,  in  differ- 
ent parts  of  the  world,  must  now  be  impossible;  because, 
among  some  nations,  it,  undoubtedly,  would  have  been 
considerably  advanced,  by  fortunate  accidents  and  in- 
structive observations,  long  before  they  had  learned  to 
write  histories  and  record  facts;  and,  indeed,  almost  all 
the  progress  which  had  been  made  in  dyeing,  until  with- 
in a  few  years,  must  have  resulted  from  such  causes; 
depending,  as  it  does,  for  its  principles  upon  chemistry, 
which  was  by  much  too  defective  to  afl'ord  any  conside- 
rable assistance,  either  to  practical  dyers,  or  speculative 
men,  who  might  have  wished  to  study  and  improve  the 
art;  and,  therefore,  it  happened,  as  might  have  been  ex- 
pected,  that  the  practice  of  dyeing  had,  by  the  fortui- 
tous discoveries  of  great  numbers  of  individuals  cm- 
ployed  in  it,  been  carried  so  far  before  the  theory^  that 
the  latter  was  as  little  capable  of  explaining^  as  it  had 
been  of  suggesting,  the  most  beneficial  effects  produced 
by  it;  and  this,  probably,  was  at  least  one  reason  why 
dyeing  was  so  much  neglected  among  the  philosophers 
of  Greece  and  Rome,  though  they  highly  esteemed  the 
arts  of  painting,  sculpture,  &c. 

Notwithstanding  the  great  importance  of  alum  in  dye- 
ing, it  is  not  probable  that  mankind,  with  their  natural 
disposition  to  admire  gaudy  colours,  and  seek  personal 
distinctions,  should  have  delayed  the  application  even 
of  adjective  dyeing  matters,  to  their  clothing,  until  they 
had  become  acquainted  with  alum  and  its  effects,  in 


xxviii  Introduction, 

raising  and  fixing  the  colours  afforded  by  tliese  mat- 
ters. Such  an  acquaintance  would  not,  in  the  ordinary 
course  of  events,  be  acquired,  until  some  progress  had 
been  made  in  civilization;*  and  there  are  many  facts  to 
prove  that,  in  much  ruder  states  of  society,  men  have 
attempted  to  dye  their  dothiiigif  and  as  these  attempts 
would  have  proved  more  successful  upon  wool  than 
upon  linen,  or  cotton,  by  reason  of  the  greater  affinity 
of  the  former  to  some  adjective  colouring  matters,  (as 
lately  noticed,)  we  may  conclude,  that  in  climates  which 
required  clothes  of  wool,  the  dyeing  of  these  would  have 
been  practised  much  earlier  than  that  of  linen  or  cot- 
ton.J  And,  accordingly,  Pliny  mentions  dyed  linen  as 

*  Clavigero,  in  his  history  of  Mexico,  pretends  that  the  Mexi- 
cans used  the  earth  of  alum  to  produce  certain  colours:  that,  after 
grinding  and  dissolving  the  aluminous  earth,  which  they  called 
tlalxocotly  they  hoiled  it  in  earthen  vessels,  and  then,  by  distillation, 
extracted  the  alum  pure,  white  and  transparent;  and  that,  before 
they  hardened  it  entirely,  they  divided  it  in  pieces  to  sell  in  the 
imarket.  To  a  chemical  reader  this  will  sufficiently  discover  the 
ignorance  of  the  historian  in  regard  to  the  eiFect  of  distillation,  &c. 
What  foundation  this  account  may  have  had  in  other  respects  I 
know  not. 

t  Of  the  nature  of  these  attempts,  and  the  value  of  some  at  least 
of  the  colours  produced  by  them,  we  may  judge,  by  the  mention 
which  Pliny  has  made  of  a  purple  dyed  for  the  clothing  of  inferior 
people  among  the  Gauls,  from  "  vaccinia;"  by  which  either  the 
ripe  privet,  or  the  whonle  berries,  are  supposed  to  have  been 
meant.  See  lib.  xvi.  c.  18.  He  also  mentions  violets  as  being  used 
to  produce  a  purple. 

\  Uncivilized  nations  appear,  in  some  instances  at  least,  to  have 
found  means  to  mcrease  this  affinity^  particularly  by  the  use  of  ve- 
getable acids.  The  savage  tribes  of  North  America,  had  long  been 
accustomed  to  dye  certain  animal  substances,  such  as  feair.  feathers, 
and  porcupine  quills,  of  blight  rtd  and  yellow  colours,  whilst  they 
were  wholly  unacquainted  with  the  use  ©f  aium;  and  having  been 
informed,  that  the  red,  so  dyed,  was  produced  from  the  galium 
tinctoriiin,  and  the  acid  berries  of  the  scarlet  sumach,  lately  men- 
tioned, 1  made  trial  of  them  upon  broadcloth  without  aluiiiy  and 


Introduction,  xxix 

havinp^  been  seen  for  the  first  time,  in  the  fleet  with 
which  Alc-xander  the  Great  had  navij^ated  the  river  In- 
dus^ when  his  captains,  in  skirmishini^j  with  the  Indians 
upon  its  banks,  to  their  astonishment  suddt-nly  clianged 
the  ensigns  of  their  vessels,  and  displayed  flags  of  va- 
rious colours  wavering  in  the  wind.^  It  nlust,  however, 
be  confessed  that,  according  to  Pliny's  account,  the  dye- 
ing even  of  woollen  clothes  had,  at  that  time,  made  but 
little  progress,  at  least  in  regard  to  the  finer  colours; 
for,  in  the  eighth  chapter  of  his  twenty-first  book,  after 
declaiming  against  the  luxury  of  his  cotemporaries,  in 

produced  a  red  colour,  inclining  to  the  orange,  of  considerable 
brii^htness.  which,  being  exposed  with  a  red  less  inclining  to  the 
orange,  which  I  had  dyed  also  from  the  roots  of  galium  linctorum 
only,  but  upon  broadcloth,  prepared  as  usual  with  alum  and  tartar, 
I  found,  at  the  end  of  two  months,  that,  though  the  latter  had  suf- 
fered least,  the  other  with  sumach  berries  was  much  better  and 
more  lasting  than  I  had  supposed  it  possible  to  produce  without 
some  basis.  1  have  since  been  informed,  that  the  acid  juice  of  the 
crab  apple  is  sometimes  employed  by  the  tribes  in  North  America 
for  the  same  purpose;  and  that  professor  Woodhouse,  of  Philadel- 
phia, supposes  himself  to  have  discovered  alumine  in  the  very  acerb 
fruit  of  the  diospyros  virginiana,  or  persimmon  tree,  which,  if  this 
supposition  be  well  founded,  may  be  expected  to  produce  still  bet- 
ter effects  as  a  mordant  for  dyeing,  than  either  of  the  acids  before 
mentioned;  unless  the  latter,  as  some  have  supposed,  should  also 
contain  alum.  Indeed,  Loureiro  (torn.  i.  p.  315.)  has  described  a 
tree,  under  the  name  of  decadia  aluminosOy  of  which  he  says  the 
bark,  and  more  especially  the  dried  leaves,  are  in  great  use  among 
the  dyers  of  Cochinchina,  to  exalt  and  Jix  their  colours.  "  Magni 
usus  sunt  infectoribus  indigenis  in  tingendis  lelis  quarum  colores 
decocto  illorum  nitide  exaltantur  et  Jirmantur.**  This  statement, 
joined  to  the  specific  name  of  aluminosa,  appears.to  indicate  that 
the  bark  and  leaves  of  this  tree  either  contain  alumine^  or  are 
thought  capable  of  answering  the  purposes  of  alum  as  a  mordant. 
*  **  Tentatum  est  tingi  linum,  quoque  et  vestium  insaniam  acci- 
pere,  in  Alexandri  Magni  primum  classibus,  Indo  amne  navigantis, 
cu  J  cu'  es  ejus  et  prefecti  certamine  quodam  variassent  insignia 
navium;  siupueruntque  littora,  flatu  versi  coloria  implente." 


XXX  Introduction: 

wearing  clothes  dyed  of  colours  which  emulated  those 
of  the  finest  natural  flowers,  he  observes,  that  none  of 
these  flowery  colours  ("  flores")  were  in  use  during  the 
life  of  Alexander  the  Great;  though,  says  he,  nobody 
doubts  of  their  having  been  borrowed  by  the  Romans 
from  the  Greeks;  for  how  else,  he  asks,  should  the 
names  which  they  still  retain  in  Italy,  have  been  all 
Grecian,  ''  a  Grsecis  tamen  repertos  quis  dubitet;  non 
aliter  Italia  usurpante  nomina  illorum?" 

Probably,  the  companions  of  Alexander,  when  he  in- 
vaded Persia  and  India,  became  acquainted  with  the  rich 
dyes  of  those  countries;  and  afterwards  made  some,  at 
least,  of  them  known  to  the  Greeks,  among  whom,  as 
well  as  among  the  Romans,  the  wearing  of  undyed 
clothes,  (which  Pliny  has  denominated  ^^  panni  nativi 
eoloris,^')  had  been  immemorially  practised  by  the  great 
mass  of  people.*  We  are  not,  however,  to  understand 
that  dyed  clothes  were  not  in  much  higher  estimation 
than  the  undyed,  as  soon  as  they  were  made  known, 
for  this,  undoubtedly,  was  the  fact;  but  they  were  too 
costly  to  be  used  by  any  but  the  rich  and  great,  or  for 
the  service  of  religion,  or  upon  extraordinary  occasions. 
See  Exodus,  chapters  26,  28,  38,  and  39.  See  also  Plu- 
tarch, de  Iside  and  Osiride,  c.  78,  where  he  tells  us, 
that  the  robes  or  sacred  vestments  of  Isis,  were  of  va- 
rious colours;  but  those  of  Osiris  were  of  one  bright  co- 
lour. Juno,  Venus,  and  Proserpine,  were  by  the  ancient 
poets  commonly  represented  as  being  robed  in  purple; 
and  we  are  told,  in  the  37th  chapter  of  Genesis,  that 
Jacob  "  loved  Joseph  more  than  all  his  children,  be- 
cause he  was  the  son  of  his  old  age;  and  he  made  him 

*  As  these  undyed  clothes  often  wanted  cleaning,  this  operation 
gave  employment  to  a  description  of  people  called  fullones,  who 
were  properly  scourers,  though  the  clothes  would  naturally  be 
thickened  or  fulled,  in  some  degree,  whilst  in  their  hands. 


In  troduction.  x  x  x  i 

a  coat  of  colours:'*^  a  distinction  which  caused  Joseph  to 
be  hated  by  his  brothers;  and  afterwards  to  be  sold  by 
them,  and  carried  into  Egypt. 

Of  the  substantive  colours  known  in  Greece,  and  at 
Rome,  two  (highly  deserving  of  our  notice)  were  the 
celebrated  purple  obtained  from  the  murex  and  bucci- 
num,  and  the  blue  procured  from  indigoferous  plants, 
particularly  the  woad,  (glastum  or  isatis  tinctoria):  of 
these,  and  of  their  connection  with  the  history  of  dye- 
ing, most  ample  and  interesting  accounts  will  be  found, 
in  the  4th  and  5th  chapters  of  the  first  part  of  this  work. 
Another  plant,  by  the  Romans  called  fucus,  and  which 
appears  to  have  been  no  other  than  that  species  of  lichen 
which  is  now  called  orchall^  was  in  such  general  use 
among  the  latter,  for  dyeing  a  beautiful,  though  not  du- 
rable purple,  that  the  name  of  fucus,  came  at  length  to 
be  often  used  as  signifying  generally  a  dye.  Of  this  also 
a  sufficient  account  will  be  found  at  page  216  of  this 
volume. 

In  regard  to  the  adjective  colouring  matters  for  which 
alum  or  aluminous  earths  and  other  mordants  were  em- 
ployed by  the  ancients,  I  must  observe,  that  it  seems 
difficult  to  give  a  complete  account  of  them:  though  we 
have  reason  to  conclude,  that  the  kermes  (or  coccus  illi- 
cis)  and  madder  (rubia)  were  by  much  the  most  impor- 
tant: of  these  also,  and  of  their  connection  with  the 
history  of  dyeing,  sufficient  accounts  will  be  found  in 
their  proper  places.  To  these  may  be  added  the  roots 
of  anchusa  tinctoria,  or  alkanet,  the  genista  tinctoria,  or 
dyer's  broom,  (mentioned  by  Pliny,  xvi.  c.  18.)  gall- 
nuts,  pomegranate  peels,  alder  bark,  the  rinds  of  wal- 
nuts, the  bark  of  the  walnut  tree,  and  the  pods  of  the 
Egyptian  acacia;  but  of  the  particular  methods  in  which 
these  were  employed,  or  of  the  basis  or  mordants  used 
with  them,  no  information  worthy  of  being  here  particu- 


xxxii  Introduction, 

larly  noticed  has  been  transmitted  to  us,  either  by  Greet 
or  Latin  writers.  And,  indeed,  almost  all  the  knowledge 
which  the  Greeks  and  Romans  had  obtain^-d  from  others, 
or  acquired  by  their  own  industry,  on  this  subject,  ap- 
pears to  have  been  lost  about  the  fifth  century,  when, 
as  M.  BerthoUet  has  observed,  scarce  any  traces  of  sci- 
ence or  humanity  were  left  in  the  western  empire.  A 
few  sparks  of  the  former  did,  indeed,  remain  in  Italy, 
where  they  were  in  some  degree  rekindled,  by  occa- 
sional accessions  of  knowledge,  and  of  Greek  artists 
obtained  from  the  east,  in  consequence  of  the  crusades; 
and  also,  from  the  various  importations  made  by  the 
Venetians,  of  oriental  productions  and  manufactures; 
which,  by  affording  new  materials,  and  new  objects  of 
imitation,  assisted  in  exciting  and  directing  that  indus- 
try which  had  so  long  been  dormant  in  the  west  of 
Europe. 

Italy  may,  therefore,  be  considered  as  the  cradle  in 
which  a  feeble  remnant  of  the  knowledge  of  dyeing,  as 
exercised  by  the  Greeks  and  Romans,  was  nourished 
and  invigorated,  so  as,  with  the  new  dyeing  drugs  since 
obtained  from  India  and  America,  (which  will  be  here- 
after noticed,)  and  with  the  various  subsequent  acquisi- 
tions of  chemical  and  other  knowledge,  to  have  attained 
a  state  of  improvement,  greatly  exceeding  all  former 
expectation. 

From  Italy  some  knowledge  of  dyeing,  limited  as  it 
was,  spread  itself  gradually  to  France,  Spain,  and  Flan- 
ders, whence  king  Edward  the  Third,  of  England,  pro- 
cured dyers;  and  hi  1472,  a  company  of  these  artists 
was  incorporated  in  London. 

The  Germans,  as  BischofF  informs  us,  were  slow  in 
acquiring  and  practising  the  art  of  dyeing;  excepting 
only  that  of  blacky  which  was  their  dress  or  gala  colour; 


Introduction,  xxxiii 

and  excepting  browns,  which  were  generally  wore  by 
the  monks,  and  the  common  people. 

In  France  a  division  was  established  at  a  very  early 
period,  between  the  dyers  of  lasting  colours,  who  were 
denominated  "  teinturiers  en  bon  teint,'^^  and  the  dyers 
of  fugitive  colours,  or  those  "en  petit  teint;"  and  the 
former  were  prohibited  from  using,  or  having  in  their 
possession,  the  dyeing  drugs  employed  by  the  latter.  A 
similar  distinction  was  also  established  in  Italy,  as  Bis- 
chofF  states,  on  the  authority  of  a  French  ordinance  of 
November  17,  1383. 

The  first  Italian  account  of  the  processes  used  in  dye- 
ing, as  BischofF,  and  after  him  BerthoUet,  have  inform- 
ed us,  was  published  at  Venice  in  1429,  under  the  title 
of  "  Mariegola  delV  Arte  dei  Tentori^^''  of  which  a  se- 
cond edition  appeared  in  1510.  But  the  imperfections 
of  this  work,  induced  John  Ventura  Kosetta,  overseer 
of  the  arsenal  at  Venice,  to  undertake  a  work  less  de- 
fective; and  the  better  to  execute  his  undertaking,  he 
travelled  over  different  parts  of  Italy,  and  some  other 
countries,  to  acquire  information;  from  which  he  com- 
posed, and  in  1548  published,  under  the  assumed  name 
of  Plictho,  a  collection  of  descriptions  of  the  operations 
of  dyeing,  as  then  practised,  which  BischofF  considers 
as  the  foundation  and  principal  cause  of  many  subse- 
quent improvements  in  this  art:*  though  Hellot  has 
mentioned  it  as  deserving  but  little  notice. 

*  The  title  of  this  work  was  "  Plictho  dell*  Arte  de  tentori  che 
insegna  tenger  panni,  tele,  banbasi,  e  sede  si  per  I'arte  magiore, 
eome  per  la  commune.  Vinezia,  1448,  4to."  Or  Plictho's  Art  of 
Dyeing,  which  teaches  how  to  dye  cloth,  linen,  cotton  and  silk,  of 
durable,  as  well  as  false,  or  ordinary  colours,  &c. 

BerthoUet  has  remarked,  that  there  is  no  mention  in  this  work, 
of  either  cochineal  or  indigo;  whence  he  infers,  that  neither  of 
these  important  drugs  had  then  been  employed  for  dyeing  in  Italy; 
an  inference  which,  though  probably  just,  seems  extraordinary,  con- 

VoL.  I.  e 


xxxiv  Introduction, 

Of  the  important  changes,  and  rapid  advancement, 
which  were  produced  in  dyeing  after,  and  by  the  dis- 
covery of  new  and  valuable  colouring  matters,  and  also 
of  new  bases  or  mordants,  (particularly  that  of  tin,)  suf- 
ficient accounts  are  given  in  the  course  of  this  work, 
and  to  these  I  must  refer,  to  avoid  improper  repetitions. 

The  first  or  earliest  book,  which  I  have  been  able  to 
discover  in  the  English  language,  relating  in  any  consi- 
derable degree  to  the  art  of  dyeing,  is  a  thin  and  small 
quarto  volume,  (now  before  me,)  in  black  letter,  intitled 
**  A  Profitable  Booke,  declaring  divers  approved  reme- 
dies to  take  out  spots  and  stains,  in  silkes,  velvets,  lin- 
nen  and  woollen  clothes;  with  divers  colours  how  to  die 
velvets,  and  silkes,  linnen,  and  woollen,  fustian,  and 
thread:  also  to  dress  leather  and  to  colour  felles." — 
*^  Taken  out  of  Dutch,  and  Englished  by  L.  M.  Im- 
printed at  London,  by  Thomas  Purfoot,  dwelling  with- 
in the  New  Rents  in  S.  Nicholas  Shambles,  1605." 

The  instructions  contained  in  this  last  volume,  relate 
principally  to  the  use  of  indigo,  (which  is  called  jiora 
or  floray,)  woad,  madder,  (particularly  the  crap^)  Bra- 
sil  wood,  weld,  safilower,  gall-nuts  and  alder  bark;  once 
or  twice  kermes  and  lac  are  mentioned;  but  not  cochi- 
neal. These  instructions  seem  to  be  founded  chiefly 
upon  the  practices  of  the  dyers  in  Flanders,  where  the 
art  at  that  time  was  making  considerable  progress;  but 
as  black  was  the  colour  in  most  general  use,  the  re- 
ceipts, if  I  may  so  call  them,  for  producing  it,  are  in 
number  equal  to  almost  all  the  others.  After  this,  no- 
thing seems  to  have  been  done  in  this  country  to  in- 
form or  assist  practical  dyers,  until  the  year  1662,  when 
the  Royal  Society,  then  recently  formed,  at  their  meet- 

sidering  the  facts  which  will  be  found  in  the  fifth  chapter  of  the 
first  part,  and  the  third  chapter  of  the  second  part  of  this  work. 


Introduction,  xxxv 

ing  on  the  30th  of  April,  desired  Mr.  Haak  to  translate 
into  the  English  language  the  work  which,  more  than 
half  a  century  before,  had  been  published  in  Italy,  un- 
der the  name  of  Plictho,  (though  this  has  never  been 
done;)  and,  on  the  same  day,  Sir  William  Petty,  one  of 
its  earliest  and  most  active  members,  in  consequence  of 
a  previous  request  from  the  Society,  brought  in  "  An 
Apparatus  to  the  History  of  the  Common  Practices  of 
Dyeing,"  which  was  afterwards  printed  in  Dr.  Spratt's 
History  of  the  Royal  Society,  and  seems  to  have  been 
the  first  original^  though  summary  account  published  in 
the  English  language,  of  the  means  and  operations  used 
by  dyers. 

Nearly  two  years  afterwards,  viz.  March  30,  1664, 
the  Hon.  Robert  Boyle  presented  to  the  Royal  Society 
his  "  Experiments  and  considerations,  touching  Co- 
lours;" and,  on  the  10th  of  August  following,  it  was 
ordered  by  the  society,  "  that  the  way  ofjixing  colours 
should  be  recommended  to  Mr.  Howard,  Mr.  Boyle, 
and  Dr.  Merritt."  These,  and  especially  the  two  first, 
were  among  the  most  distinguished  members  of  the  so- 
ciety; but  it  does  not  appear  that  they  were  able  to  do 
any  thing  deserving  of  notice,  in  consequence  of  this 
recommendation.  However,  at  a  meeting  of  the  society 
on  the  11th  of  November,  1669,  that  very  ingenious, 
active,  and  useful  member,  *'Mr.  Hooke,  produced  a 
piece  of  calico,  stained  after  the  way  contrived  by  him- 
self, which  he  was  desired  to  prosecute  in  other  colours, 
besides  those  that  appeared  in  this  piece."  (Birch's  His- 
tory of  the  Royal  Society,  vol.  ii.  p.  401.)  And,  accor- 
dingly, on  the  9th  of  the  following  month,  "  Mr.  Hooke 
produced  another  specimen  of  staining  with  yellow,  red, 
green,  blue,  and  purple  colours,  which,  he  said,  would 
endure  washing  with  warm  water  and  soap."  But  from 
this  time  it  does  not  appear  that  any  thing  considerable 


xxxvi  Introduction. 

was  done,  for  nearly  the  space  of  a  century,  by  men  of 
Science  in  this  kingdom,  towards  improving  the  arts  of 
dyeing  and  caHco  printing;  they  being,  probably,  dis- 
couraged by  the  difficulties  which,  from  the  very  imper- 
fect slate  of  chemical  knowledge,  must  have  occurred, 
in  every  attempt  to  improve  upon  what  the  dyers  were 
able  to  perform,  without  any  principle  or  theory. 

In  France,  however,  that  great  minister,  Colbert, 
anxious  to  extend  the  commerce  and  manufactures  of 
his  country,  turned  his  attention  particularly  to  the  art 
of  dyeing,  with  a  view  to  amend,  as  well  as  to  obviate 
frauds  in  the  practice;  and  calling  to  his  assistance  M. 
D'Albo,  a  set  of  regulations  and  directions  were  pre- 
pared and  published  at  Paris,  first  in  1669,  and  after- 
wards in  1672,  under  the  title  of  "  Instruction  generale 
pour  la  Teinture  des  Laines  et  Manufactures  de  Laine 
de  toutes  Nuances,  et  pour  la  Culture  des  Drogues  ou 
Ingredients  qu'on  emploie."  This,  however,  was  not 
intended  merely  to  inform,  but,  as  a  legislative  act,  to 
control  the  dvers  in  their  operations.  It  continued  the 
former  division  of  them  into  two  classes;  the  one,  dyers 
c<  ^^  grand^^''  who  were  confined  to  the  colours  deemed 
lasting,  while  the  dyers  "  en  petit  teint,"^^  were  allowed 
only  to  give  those  which  were  considered  as  fugitive; 
the  drugs  to  be  employed  in  each  branch  being  also 
particularly  specified;  and  the  dyers  in  each  prohibited 
from  using,  or  having  in  their  possession,  any  of  the 
drugs  allotted  to  the  other.  Such  restraints,  though  in- 
tended to  prevent  frauds,  would  have  operated  as  checks 
upon  future  improvements,  if  the  government  had  not, 
at  the  same  time,  encouraged  useful  discoveries  in  this 
art,  first,  by  offering  particular  rewards,  and  afterwards, 
by  appouiting  those  eminent  chemists,  Dufay,  Hellot, 
Macquer,  and  Berthollet,  in  succession,  to  superintend, 
officially,  the  practice  of  dyeing  in  its  several  depart- 


Introduction.  xxxvii 

ments,  and  to  cultivate  those  branches  of  chemical  and 
other  sciences,  which  were  connected  with  the  princi- 
ples, or  capable  of  amending  the  theory,  of  that  art; 
and,  considering  the  eminent  benefits  which  have  re- 
sulted from  the  labours  of  these  men,  there  is  cause  to 
regret  the  want  of  such  an  appointment  in  this  great 
manufacturing  and  commercial  nation. 

With  Dufay's  assistance,  M.  Colbert's  *'  Instruction" 
was  amended,  or  rather  superseded  by  a  new  one,  pub- 
lished under  the  administration  of  M.  D'Orry,  in  1737. 
He  (Dufay)  appears  to  have  been  the  first  who  enter- 
tained just  conceptions  of  one  of  the  causes  of  the  ad- 
hesion of  colouring  matters  to  stuffs  when  dyed;  I  mean 
that  u^hich  depends  on  an  affinity  or  attraction  subsist- 
ing between  such  matters,  and  the  fibres  or  substance 
of  the  dyed  stuffs.  He  clearly  perceived  that  without 
this,  cloth,  while  in  the  dyeing  vessel,  could  only  ac- 
quire a  degree  of  colour  equal  to  that  of  the  dyeing  li- 
quor, by  an  equal  participation  of  the  colouring  matter 
dissolved  therein;  whereas,  in  fact,  the  cloth  is  often 
seen  to  exhaust,  by  attracting  to  itself  all  the  tingent 
particles  of  the  dyeing  liquor,  so  as  to  leave  it  as  co- 
lourless as  water.  He  also  noticed  the  difference  in  the 
degrees  of  attraction,  which  different  substances,  as  wool 
and  cotton,  exert  upon  the  same  colouring  matters;  and 
which  he  found  so  great,  that  a  skein  of  each  having 
been  in  an  equal  degree  subjected  to  the  means  and 
operations  commonly  employed  for  dyeing  scarlet,  the 
woollen  yarn  was  found  to  be  fully  and  permanently 
dyed  of  that  colour,  while  the  cotton  retained  all  its 
former  whiteness.*  He  appears,  however,  to  have  had 
no  conception  of  the  other  and  more  important  cause 

*  Observations  Physiques  sur  le  Melange  de  quelques  Couleurs 
dans  la  Teinture.  Memoires  de  TAcademie  Royale,  8cc.  1737. 


xxxviii  Introduction, 

of  the  permanency  of  adjective  colours,  I  mean  that 
which  arises  from  the  interposition  of  a  suitable  basisy 
possessing  a  particular  attraction  both  for  the  colouring 
matter  and  for  the  dyed  substance,  and  thereby  acting 
as  a  bond  oj* union  between  them:  nor  did  his  successor, 
Hellot,  ever  approach  nearer  to  the  truth  on  this  sub- 
ject. He,  (Hellot,)  indeed,  published  an  excellent  prac- 
tical treatise  on  the  art  of  dyeing  wool  and  woollen 
cloths,  in  which  the  several  processes  were  very  accu- 
rately described:  but  in  reasoning  upon  the  facts  stated 
therein,  he  adopted,  and  suffered  himself  to  be  grossly 
misled  by,  a  frivolous  hypothesis,  devoid  of  the  least 
foundation  in  truth.  He  fancied  that  he  could  discover, 
in  every  dyeing  process,  some  means  by  which  sulphate 
of  potash  (then  called  vitriolated  tartar)  might  be  form- 
ed; and  this  neutral  salt  not  being  readily  soluble  by 
cold  water,  nor  by  air  or  light,  he  conceived  the  whole 
art  of  dyeing  to  consist  in  first  dilating  the  pores  of  the 
substance  to  be  dyed,  so  as  to  procure  a  copious  admis- 
sion of  colouring  matter,  divided  by  a  suitable  prepara- 
tion into  atoms,  and  then  wedging  or  fastening  these 
atoms  within  the  pores  of  the  dyed  substance,  by  the 
small  particles  or  crystals  of  this  difficultly  soluble  neu- 
tral salt.  Upon  this  mechanical  hypothesis,  he  supposed 
that  alum  became  useful  in  dyeing,  not  by  the  pure  clay 
or  alumine  which  it  contains,  and  which  alone  contri- 
butes to  fix  any  colouring  matter,  but  by  furnishing 
(and  only  by  furnishing)  sulphuric  or  vitriolic  acid,  to 
assist  in  forming  the  sulphate  of  potash,  which  was  to 
perform  this  important  function  of  wedging  or  fastening 
the  colouring  atoms;  though,  if  he  had  brought  this  vi- 
sionary hypothesis  to  the  test  of  experiment,  as  might 
have  been  easily  done,  he  would  have  found,  not  only 
that  no  sulphate  of  potash  existed,  in  many  of  the  cases 
where  he  supposed  it  to  produce  such  important  effects, 


Introduction,  xxxix 

but  also  that,  even  if  intentionally  formed  and  employ- 
ed for  this  purpose,  it  possessed  no  power  whatever  of 
fixing  any  colouring  matter  yet  known.  But  though 
nothing  could  be  more  groundless  than  this  theory,  the 
learned  in  all  countries  appear  to  have  been  satisfied 
with  it  for  a  considerable  length  of  time,  it  being  always 
less  troublesome  to  believe  than  to  make  experiments. 
The  late  celebrated  Macquer,  in  a  Memoir,  printed 
among  those  of  the  Royal  Academy  of  Sciences  for 
1749,  mentioning  Hellot  and  his  hypothesis,  says,  *'ce 
savant  chimiste  est  le  premier  qui  ait  porte  le  fiamheau 
de  la  physique,  dans  Part  obscur  de  la  teinture,  et  qui 
ait  rassemble  et  mis  en  ordre,  suivant  les  principes 
d'une  theorie  ingenieuse,  les  phenomenes  et  les  opera- 
tions bizarres  de  cet  art:  il  a  mis  les  chimistes  a  portee 
de  voir  clair,  dans  ce  chaos  tenebreux."  And  after- 
wards, in  his  preface  to  his  Treatise  on  dyeing  SilJ^, 
published  in  1763,  he  makes  this  observation:  '*  ce  se- 
roit  ici  le  lieu  d'expliquer  la  maniere  dont  les  mordants 
agissent  dans  la  teinture,  et  de  developper  la  cause  du 
bon  et  du  faux  teint;  mais  ces  objets  ont  ete  traites 
avec  tant  de  segacite  par  M.  Hellot,  que  je  crois  devoir 
y  renvoyer  le  lecteur;"  and  even  so  lately  as  the  year 
1766,  in  an  eulogium  pronounced  upon  Hellot,  in  the 
Royal  Academy  of  Sciences,  and  published  with  the 
Memoires  for  that  year;  the  secretary,  after  explaining 
Hellot's  hypothesis,  says,  *'  a  I'aide  de  cette  theorie  si 
lumineuse,  on  ne  sera  plus  trompe  dans  la  pratique  de 
cet  art,  que  lors  qu'on  voudra  bien  I'etre." 

Before  this  time,  viz.  1748,  Scheffer  published  a  small 
work  on  dyeing,  which  Bergman  afterwards  thought  wor- 
thy of  being  republished,  with  notes  written  by  himself. 
It  related  in  a  great  degree  to  the  application,  for  the 
benefit  of  the  Swedish  manufactures,  of  the  indigenous 
dyeing  plants  of  that  kingdom;   in  search  of  which. 


xl  Introduction, 

Linnaeus  afterwards  undertook  his  Iter  Gothlandicum. 
Scheffer  was  thought  to  have  made  discoveries  of  con- 
siderable importance  in  dyeing;  but  not  having  been 
published,  most  of  them  were  lost,  as  Bergman  informs 
us. 

Mr.  Henry,  of  Manchester,  has  observed,  that  Mr. 
Keir,  the  ingenious  translator  of  "  Macquer's  Chemical 
Dictionary,  appears  to  have  been  the  first  who  suspect- 
ed that  (in  dyeing)  the  earth  of  alum  was  precipitated, 
and  in  this  form  attached  to  the  material  prepared  or 
dyed;''  and  this  idea,  having  been  published,  was  adopt- 
ed by  Mr.  Macquer,  and  farther  extended  in  the  last 
edition  of  his  "  Dictionnaire  de  Chimie,"  at  the  article 
*'  Teinture,"  where  he  seems  to  have  formed  just  con- 
ceptions of  the  nature  and  uses  of  alum,  and  of  different 
metallic  solutions,  as  mordants,  in  dyeing.*  This  edi- 
tion was  published  in  the  year  1778,  and  Mr.  Macquer 
soon  after  announced  a  design  of  writing  a  general  trea- 
tise on  the  art  of  dyeing,  which  his  death,  however, 
frustrated.  Some  time  after  Mr.  Macquer's  decease, 
Mr.  Henry  favoured  the  public  with  a  very  interesting 
paper,  (in  the  third  volume  of  the  Memoirs  of  the  Man- 
chester Society,)  "  On  the  nature  of  Wool,  Silk,  and 
Cotton,  as  objects  of  the  art  of  Dyeing;  on  the  various 

*  Berthollet  considers  Bergman,  as  being  the  first  who  ascribed 
the  fixing  of  colours,  by  dyeing,  to  particular  affinities;  and  I  cannot 
now  readily  ascertain  dates  so  accurately  as  to  decide  whether  he 
did  this  previously  to  Mr.  Keir's  publication  of  the  translation  of 
Macquer's  Dictionary. 

Perhaps  it  may  be  allowable  for  me  to  observe,  that,  in  a  com- 
munication which  I  made  to  the  Royal  Society  in  1773,  mentioned 
in  the  last  chapter  of  this  work,  I  distinctly  ascribed  the  production 
of  ink  and  the  black  dye  to  this  affinity  between  iron  and  the  co- 
louring matter  of  galls,  and  so  far,  at  least,  I  had  anticipated  both 
Kier  and  Bergman.  The  first  publication  by  the  latter,  on  this  sub- 
ject, was,  I  believe,  in  1776. 


Introduction,  xli 

preparations  and  mordants  requisite  for  these  different 
substances;  and  on  the  nature  and  properties  of  co- 
louring matter,  &c.:"  a  paper  replete  with  useful  infor- 
mation, and  ingenious  ideas,  (particularly  respecting  the 
causes  of  the  durability  of  what  is  called  the  Turkey 
red,)  and  which  deservedly  reflects  great  credit  on  the 
author's  talents  and  acquirements.  And  in  the  year 
1791,  that  most  excellent  chemist,  M.  Berthollet,  who 
had  been  appointed  by  the  government  of  France  to 
succeed  M.  Macquer  in  superintending  the  arts  con- 
nected with  chemistry,  and  particularly  dyeing,  pub- 
lished a  work  of  great  merit,  under  the  title  of  "  Ele- 
mens  de  PArt  de  la  Teinture,"  in  two  volumes,  which 
has  been  translated  into  English  by  Dr.  Hamilton.^ 

Before  the  publication  of  M.  Berthollet's  work,  I  had 
collected  most  of  the  materials  for  this  undertaking;  and, 
though  he  has  anticipated  many  things  which  I  was  pre- 
pared to  mention,  (some  of  which  I  shall  notwithstand- 
ing mention  in  my  own  way,)  this  production  aflTorded 
me  great  pleasure,  as  well  as  profit;  because  the  author's 
superior  chemical  knowledge  has  enabled  him  to  take 
just  views  of  many  intricate  parts  of  his  subject,  and  to 
reason  with  great  solidity,  as  well  as  sagacity,  upon 
most  of  the  operations  of  dyeing.  He  has,  moreover, 
enabled  me  to  abridge  my  own  work,  by  referring,  as  I 
must  do,  to  his,  for  more  ample  information  upon  seve- 
ral topics,  particularly  those  of  fuel,  the  different  acids, 
alum,  the  sulphates  of  iron,  copper,  and  zinc,  verdi- 
grise,  acetite  of  lead,  the  different  alkalies,  soap,  sul- 
phur, arsenic,  and  w^ater,  of  all  which  he  has  treated  so 

•  Since  the  above  was  written  in  1794,  a  new  and  imfiroved  edi- 
tion  of  the  "  Elemens  de  TArt  de  la  Teinture"  has  been  published 
by  M.  Berthollet,  conjointly  with  his  son,  (lately  deceased,)  and  all 
my  quotations  from  the  Elements,  &c.,  are  to  be  understood  to 
have  been  made  from  this  new  edition,  unless  the  contrary  be  stated. 

Vol.  I.  f 


xlii  Introduction, 

ably  and  fully  as  to  leave  but  very  little  for  me  to  add 
respecting  any  of  them. 

But  though  I  have  been  preceded  by  authors  of  such 
distinguished  ability  as  Mr.  Henry  and  M.  BerthoUet, 
the  new  facts  and  observations  which  I  here  offer  to  my 
readers,  will  show  that  I  did  not  find  the  subject  ex- 
hausted. And,  indeed,  it  is  so  far  inexhaustible,  that  it 
probably  will  afford  ample  employment  for  the  greatest 
talents  and  industry  during  many  generations. 

In  justice  to  that  very  eminent  and  respectable  che- 
mist, M.  Chaptal,  I  ought  to  mention  that  his  excellent 
work,  intitled  *'  Elemens  de  Chimie,'*  (in  three  vo- 
lumes,) contains  many  ingenious  facts  and  observations 
relating  to  the  causes  of  the  production  and  changes  of 
colours,  as  well  as  to  several  other  subjects  connected 
with  dyeing:  and  to  these  he  has  since  made  consider- 
able additions  in  his  most  valuable  work,  intitled  **  Chi- 
mie  appliqu6e  aux  Arts,"  in  four  volumes  octavo,  which 
was  published  soon  after  he  had,  with  great  difficulty, 
obtained  permission  to  resign  his  office  of  minister  of 
the  interior  of  France,  and  return  to  his  early  and  fa- 
vourite pursuits. 

M.  Vitalis,  of  Rouen,  has  also  recently  published  a 
small  but  useful  work,  intitled,  Manuel  du  Teinturier 
sur  fil  ct  sur  colon  file. 

Some  other  works  deserving  of  notice  have  also,  with- 
in a  few  years,  been  published  on  this  subject,  particu- 
larly a  French  translation  of  that  of  Scheffer,  with  notes, 
by  the  celebrated  Bergman;  another  by  Poerner,  which 
has  been  translated  into  French  from  the  German,  and 
published  with  notes  by  Desmarets  and  BerthoUet;  and 
a  third  by  Dambourncy;  but  neither  of  these  has  done 
much  towards  improving  the  theory  of  dyeing.  That  of 
Poirner  contains  an  account  of  many  experiments  made 
by  the  author,  with  different  dyeing  drugs;  but,  unfor- 


Introductions  xliii 

tunately,  his  reasonings  upon  them,  and  upon  every 
part  of  the  subject,  are  highly  defective.  Dambourney 
(a  respectable  merchant)  was  possessed  of  no  chemical 
science,  and  he  has  done  little  more  than  give  an  ac- 
count of  the  trials  vi^hich  he  made  with  a  considerable 
number  of  vegetable  matters;  few  of  which  are  likely  to 
be  ever  much,  if  in  any  degree,  employed  by  dyers. 

Calico  printing,  though  practised  for  many  ages  in 
some  parts  of  Asia,  seems  not  to  have  been  seriously 
attempted  in  Europe,  until  the  eighteenth  century;  and 
its  progress,  as  well  as  introduction,  were,  for  a  consi- 
derable time,  chiefly  the  result  of  British  ingenuity  and 
industry.  Of  their  effects,  some  account  will  be  given 
at  p.  253  et  seq.  of  this  volume;  and  I  shall  only  add 
here,  that,  about  the  year  1750,  it  was  computed  that 
fifty  thousand  pieces  of  linen  and  calico  were  annually 
printed  in  Great  Britain,  and  chiefly  in  the  neighbour- 
hood of  London;  though,  at  that  time,  there  was  no  ca- 
lico printing  in  France,  and  the  French  government,  to 
favour  their  silk  manufactures,  had  prohibited,  under 
severe  penalties,  the  wearing  of  chintzes,  and  printed 
linens  and  cottons.  In  1759,  however,  these  prohibitions 
were  annulled. 

Eminent  writers  have  derived  the  arts  of  dyeing  and 
calico  printing  from  a  considerable  degree  of  perfection, 
which  they  suppose  chemistry  to  have  somewhere  at- 
tained in  remote  ages,  though  afterwards  lost;  and  they 
imagine  that  particular  processes  of  the  art  were  pre- 
served after  the  principles  on  which  it  was  founded  had 
been  forgotten.*  I  am  not  able,  however,  to  perceive 
any  sufiicient  ground  for  these  opinions.  In  fact,  there 

*  See  Mr.  Henry's  paper  in  the  third  volume  of  the  Memoirs  of 
the  Manchester  Society.  Also  Hist,  and  Memoires  de  I'Acad.  R 
des  Sciences,  &c.  1750,  and  1766. 


xliv  Introduction. 

is  no  good  reason  to  believe,  that  chemistry  ever  had 
made  any  such  progress  among  the  ancients,  or  that 
they  ever  were  so  much  tngagcd  in  the  pursuit  of  know- 
ledge by  experiment,  as  would  have  been  necessary  for 
the  acquisition  of  but  a  moderate  portion  of  chemical 
science.*  Even  the  operations  of  calico  printing,  as 
practised  by  the  people  of  India,  and  which,  above  all 
others,  have  been  considered  as  the  result  of  an  im- 
proved state  of  chemistry,  are,  in  many  respects,  highly 
inconvenient,  and  incumbered  with  useless  parts,  which 
a  little  chemical  knowledge  would  have  taught  them  to 
reject,  as,  indeed,  they  were  rejected  by  the  people  of 
Europe,  very  soon  after  calico  printing  began  to  be 
practised  here,  though  it  began  and  was  continued  for 
some  time  with  very  little  aid  from  chemical  science. 
And,  considering  how  far  many  of  the  operations  of 
dyeing  and  calico  printing  have  been  carried  towards 
perfection,  unassisted  by  principles,  we  may  say  of  this 
art,  or,  until  very  lately,  might  have  said  what  Lord 
Bacon  says  of  music,  that  "  the  practice  has  been  well 
pursued,  and  in  good  variety,  but  the  theory  weakly; 
especially  as  to  assigning  the  causes  of  the  practice." 
Bacon's  Works,  by  Mallet,  vol.  iii.  p.  29. 

But  though  the  observations  of  many  individuals,  oc- 
cupied with  the  means  and  operations  of  dyeing,  through 
a  long  succession  of  ages  in  different  countries,  joined 
to  very  important  accidental  discoveries  occurring  from 
time  to  time,  have  produced  great  improvements  in  this 
art,  with  very  little  help  from  theory,  we  are  not  to  infer 
that  a  knowledge  of  its  true  principles,  and  of  the  causes 

^  *  Pliny  observes,  that  dyeing  had  never  been  considered  as  a 
liberal  art;  and  he  alleges  this  as  an  excuse  for  not  giving  a  rw 
tionale  of  it.  Lib.  xxii.  c-  2.  But  tliis  was  a  mere  excuse,  because 
no  degree  of  science  then  in  the  world  could  have  enabled  him  to 
do  so. 


Introduction.  xlv 

which  operate  in  producing  its  various  effects,  will  not 
prove  useful  in  the  highest  degree;  for,  (as  Mr.  Henry 
has  well  observed,)  "  though  long  experience  may  es- 
tablish a  number  of  facts,  yet,  if  the  rationale  of  the 
manner  by  which  they  are  produced  be  not  understood, 
misapplications  are  liable  to  be  made;  similar  practices 
are  pursued  where  the  cases  differ  essentially;  and  im- 
provements are  attempted  at  hazard,  and  often  on  false 
principles."  And  in  confirmation  of  these  truths,  per- 
haps I  cannot  better  conclude  this  Introduction,  than 
by  adding  the  following  quotation  from  the  History  and 
Memoirs  of  the  Royal  Academy  of  Sciences  at  Paris, 
for  the  year  1761,  viz. 

"  La  description  des  arts,  faite  avec  une  exactitude 
eclairee,  depouillee  de  toutes  les  pratiques  inutiles,  que 
Vignorance  toujours  mysterieuse  y  accumule  sans  cesse, 
et  reduite  aux  principes  constans  de  la  saine  theorie,  est 
peutetre^  le  moyen  le  plus  propre  a  hater  leur  perfection^ 
et  a  rendre  plus  abondantes  ces  sources  de  biens  et  de 
commodites,  que  i'etre  supreme  a  voulu  que  les  hommes 
dussent  a  leur  travail,  et  a  leur  Industrie." 


PHILOSOPHY 


OF 


PERMANENT  COLOURS. 


EXPERIMENTAL  RESEARCHES 

cojfCEBSijra  tub 

PHILOSOPHY 


PERMANENT  COLOURS 


PART  L 


CHAPTER  I. 
Of  the  Permanent  Colours  of  Natural  Bodies. 

**€eux  qui  exigent  qu*on  leur  donne  la  raison  d'un  effet  general ^  ne  connoissent,  iii 
"Teteiidue  de  la  nature,  ni  lesUinites  de  I'esprit  kumain." — M.  de  Buffojt. 

The  subject  of  this  chapter  was  covered  with  dark- 
ness, until  the  immortal  Newton  threw  light  upon  it,  by 
dissecting,  if  I  may  so  express  myself,  the  matter  of 
light  itself.  By  his  experiments  we  have  been  taught, 
that  "  the  light  of  the  sun  consists  of  rays  differently 
rejrangible;^^  and  that,  when  separated  by  the  prism,  in 
consequence  of  their  different  degrees  of  refrangibility, 
they  afford  all  the  various  shades  of  colour,  running 
gradually  into  each  other,  according  to  their  particular 
degrees  of  refrangibility;  the  violet  being  most  refract 
ed;  the  indigo  next;  then  the  blue,  green,  yellow,  orange, 
and  red,  which  last  is,  of  all  others,  the  least  refracted; 
that  the  same  rays  also  differ  in  degrees  of  reflexibility, 
according  to  their  degrees  of  refrangibility. 

That  the  proper  colour  of  homogeneal  light,  depend- 
ing on  its  particular  degrees  of  refrangibility,  cannot  be 

Vol.  I.  A 


2  Philosophy  of  Permanent  Colours. 

changed  by  reflections  or  refractions;  and  '*  If  the  sun's 
light  consisted  of  but  one  sort  of  rays,  there  would  be 
but  one  colour  in  the  whole  world,"  nor  the  possibility 
of  producing  any  new  colour  by  reflections  and  refrac- 
tions; and,  therefore,  "  that  the  variety  of  colours  de- 
pends upon  the  composition  of  light." 

That  "  colours,  in  an  object,  are  nothing  but  a  dispo- 
sition to  reflect  this  or  that  sort  of  rays,  more  copiously 
than  the  rest;  in  the  rays,  they  are  nothing  but  their 
dispositions  to  propagate  this  or  that  motion  into  the 
sensorium;  and  in  the  sensorium,  they  are  sensations  of 
those  motions,  under  the  Jorms  of  colours,'''* 

That  **  colours  may  be  produced  by  composition, 
which  shall  be  like  to  the  colours  of  homogeneal  light, 
as  to  the  appearance  of  colour,  but  not  as  to  the  immu- 
tability of  colour,  and  constitution  of  light;  and  those 
colours,  by  how  much  they  are  more  compounded,  by 
so  much  are  they  less  full  and  intense;  and  by  too  much 
composition  they  may  be  diluted  and  weakened,  till 
they  cease,  and  the  mixture  becomes  grey.  There  may 
be  also  colours  produced  by  composition,  which  are  not 
fully  like  any  of  the  colours  of  homogeneal  light." 
**  For  a  mixture  of  homogeneal  red  and  yellow,  com- 
pounds an  orange,  like,  in  appearance  of  colour,  to  that 
orange,  which,  in  the  series  of  unmixed  prismatic  co- 
lours, lies  between  them;  but  the  light  of  one  orange  is 
homogeneal  as  to  the  refrangibility,  and  that  of  the 
other  is  heterogencal;  and  the  colour  of  the  one,  if 
viewed  through  a  prism,  remains  unchanged;  that  of 
the  other  is  changed,  and  resolved  into  its  component 
colours,  red  and  yellow.  And  after  the  same  manner, 
other  neighbouring  homogeneal  colours  may  compound 
new  col(jurs,  &c."  And  if  to  a  colour  so  compounded, 
other  colours  be  added  in  sufficient  quantities,  they 
will  gradually  overcome  the  first,  and  produce  **  white- 


Philosophy  of  Permanent  Colours.    .  3 

ness,  or  some  other  colour."  *'  So  if  to  the  colour  of  any 
homogeneal  light,  the  sun's  white  light,  composed  of  all 
sorts  of  rays,  be  added,  that  colour  will  not  vanish  or 
change  its  species,  but  be  diluted;  and  by  adding  more 
and  more  white,  it  will  be  diluted  more  and  more,  per- 
petually." "  Lasdy,  if  red  and  violet  be  mingled,  there 
will  be  generated,  according  to  their  various  propor- 
tions, various  purples,  such  as  are  not  like,  in  appear- 
ance, to  the  colour  of  any  homogeneal  light;  and  of 
these  purples,  mixed   with  yellow  and  blue,  may  be 
made  other  new  colours."  "  That  whiteness,  and  all 
grey  colours  between  white  and  black,  may  be  com- 
pounded of  colours,   and  the   whiteness  of  the  sun's 
light,  is  compounded  of  all  the  primary  colours  mixed 
in  due  proportion."    To  illustrate  this,  he   produced 
whiteness^  first  by  a  mixture  or  re- union  of  the  several 
prismatic  colours,  and  then,  as  he  asserts,  by  mixtures 
of  differently-coloured  substances,  in  due  proportions.^ 
Each  particular  colour  being,  therefore,  a  property  of 
that  particular  sort  of  ray  which  produces  the  percep- 
tion thereof.  Sir  Isaac  Newton  concludes,  that  the  per- 
manent colours  of  natural  bodies  arise  from  hence,  that 
some  of  them  **  reflect  some  sorts  of  rays,  others  other 
sorts,  more  copiously  than  the  rest.  *  Minium  reflects 
the  least  refrangible,  or  red  making  rays  most  copious- 
ly, and  thence  appears  red.    Violets  reflect  the  most 
refrangible  most  copiously,  and  thence  have  their  co- 
lour, and  so  of  other  bodies;  and,  "  whilst  bodies  be- 
come coloured,  by  reflecting  or  transmitting  this  or  that 

*  This  last  assertion  appears  incredible,  unless  the  coloured  sub- 
stances were  all  transfiarent.  A  painter,  I  am  confident,  would 
never  produce  ivhite  from  any  or  all  of  the  several  opaque  colours, 
in  whatever  proportions  they  might  be  mixed;  and  the  Dyer  who 
should,  in  the  usual  ways,  apply  them  to  a  piece  of  white  cloth, 
would  soon  find  it  become  black. 


4  Philosophy  of  Permanent  Colours, 

sort  of  rays  more  copiously  than  the  rest,  it  is  to  be  con- 
ceived that  they  stop  and  stifle  in  themselves  the  rays 
which  they  do  not  reflect.*' 

Sir  Isaac  Newton^s  demonstrations  and  illustrations 
of  this  doctrine  may  be  seen  at  large  in  the  Jirst  Book 
of  his  Optics,  to  which  I  refer,  without  intending  to 
propose  any  objection  thereto.  It  may,  indeed,  be  liable 
to  several;  but  as  these,  even  if  well  founded,  would 
not  affect  my  ultimate  conclusions,  I  shall  thus  far  ad- 
here to  the  doctrine  under  consideration. 

Sir  Isaac  Newton's  second  Book,  however,  contains 
matter  to  which  I  cannot  assent.  He  begins  it  with 
**  Observations  concerning  the  reflections,  refractions, 
and  colours  of  thin  transparent  bodies;"  and  mentions, 
what  had  been  observed  by  others,  '*  that  transparent 
substances,  as  glass,  water,  air,  &c.  when  made  very 
thin  by  being  blown  into  bubbles,  or  otherwise  formed 
into  plates,  do  exhibit  various  colours,  according  to 
their  various  thinness;  although  at  a  greater  thickness 
they  appear  very  clear  and  colourless."  And  though  he 
considers  these  colours  as  "of  a  more  difficult  conside- 
ration,^^ yet  as  **  they  may  conduce  to  farther  discove- 
ries for  completing  the  theory  of  light,  especially  as  to 
the  constitution  of  the  parts  of  natural  bodies,  on  which 
their  colours  or  transparency  depend,^'*  he  delivers  his 
own  observations  on  this  subject:  Of  these,  the  princi- 
pal was  made,  by  taking  *'  two  object-glasses,  the  one 
a  plano-convex,  for  a  fourteen-foot  telescope,  and  the 
other  a  large  double  convex,  for  one  of  about  fifty  foot^ 
and  upon  this  laying  the  other,  with  its  plane  side  down- 
wards, I  pressed  them  slowly  together,  says  he,  to  make 
the  colours  successively  emerge  in  the  middle  of  the 
circles,  and  then  slowly  lifted  the  upper  glass  from  the 
lower,  to  make  them  successively  vanish  again  in  the 
same  place.  The  colour  which,  by  pressing  the  glasses 


Philosophy  of  Permanent  Colours »     ^  5 

together,  emerged  last,  in  the  middle  of  the  other  co- 
lours, would,  upon  its  first  appearance,  look  like  a  cir- 
cle of  a  colour,  almost  uniform  from  the  circumference 
to  the  centre;  and  by  compressing  the  glasses  still  more, 
grow  continually  broader,  until  a  new  colour  emerged 
in  its  centre,  and  thereby  it  became  a  ring,  encompas- 
sing that  new  colour;  and  by  compressing  the  glasses 
still  more,  the  diameter  of  this  ring  would  increase,  and 
the  breadth  of  its  orbit,  or  perimeter,  decrease,  until 
another  new  colour  emerged  in  the  centre  of  the  last; 
and  so  on,  until  a  third,  a  fourth,  a  fifth,  and  other  fol- 
lowing new  colours  successively  emerged  there,  and 
became  rings,  encompassing  the  innermost  colour;  the 
last  of  which  was  the  black  spot;  And,  on  the  contrary, 
by  lifting  up  the  upper  glass  from  the  lower,  the  diame- 
ter of  the  rings  would  decrease,  and  the  breadth  of  their 
orbit  increase,  until  their  colours  reached  successively 
to  the  centre;  and  then,  they  being  of  a  considerable 
breadth,  I  could  more  easily  discern  and  distinguish 
their  species  than  before."  And  these  he  found  to  be 
in  succession  from  the  black  central  spot  as  follows,  viz. 
first,  blue,  white,  yellow,  and  red;  then  in  the  next  cir- 
cuit or  order,  immediately  encompassing  these,  were 
violet,  blue,  green,  yellow,  and  red;  in  the  third  circuit 
or  order,  were  purple,  blue,  green,  yellow,  and  red; 
after  this  succeeded  in  the  fourth  circuit,  green  and 
red;  then  the  fifth,  of  greenish  blue  and  red;  next,  the 
sixth,  of  greenish  blue  and  pale  red;  and  lastly,  the  se- 
venth, of  greenish  blue  and  reddish  white:  but  the  co- 
lours in  the  last  three  circuits  he  describes  as  having 
been  very  indistinct,  and  ending  in  perfect  whiteness. 
"By  looking  through  the  two  object  glasses,"  con- 
tinues he,  "  I  found  that  the  interjacent  air  exhibited 
rings  of  colours,  as  well  by  transmitting  light,  as  by  re- 
flecting it.  The  central  spot  was  now  ivhite^  and  from 


6  Philosophy  of  Permanent  Colours. 

it  the  orders  of  the  colours  were  yellowish  red;  black, 
violet,  blue,  white,  yellow,  red;  violet,  blue,  green,  yel- 
low, red,  &c.  But  these  colours  were  very  fahit  and  di- 
lute, unless  when  the  lip^ht  was  trajected  very  obliquely 
through  the  glasses.  Comparing  the  coloured  rings 
made  by  reflexion,  with  those  made  by  the  transmission 
of  light,  I  found,"  adds  he,  "  that  white  was  opposite 
to  black,  red  to  blue,  yellow  to  violet,  Sec."  And  as 
rings  of  similar  colours  were  observed  in  bubbles, 
**  blown  with  water,  first  made  tenacious  by  dissolving 
a  little  soap  in  it,"  Sir  Isaac  Newton  endeavoured  ma- 
thematically to  ascertain  the  different  comparative  thick- 
nesses of  air,  water,  and  glass,  at  which  the  several 
circuits  or  orders  of  colours  appeared  as  before  men- 
tioned, which  he  has  noted  in  a  table  prepared  for  that 
purpose,  and  from  which  this  remarkable  fact  appears, 
that  similar  colours  in  the  different  orders  occur^  and  are 
repeated  over  and  over  again  at  very  great  diversities  of 
thickness;  a  circumstance  which,  in  my  humble  opinion, 
proves  incontestably^  that  though  thickness  might  he  one^ 
it  could  not  be^  as  he  supposes,  the  only  cause  of  these  re- 
peated variations  of  colour,*  It  was,  at  that  period,  the 
fashion  to  ascribe  even  chemical  effects  to  mechanical 
causes:  alkalies  were  supposed  to  neutralize  acids,  as 
the  blade  of  a  sword  is  sheathed  by  its  scabbard;  and 
the  most  learned  physician  of  his  age,  soon  after,  thought 

*  Sir  Isaac  Newton  seems  to  have  foreseen  this  objection  to  his 
hypothesis,  and  to  have  endeavoured  to  obviate  it,  by  supposing  the 
existence  of  what  he  denominated  different  orders  of  colours;  in 
each  of  which  it  was  conceived  that  the  red,  orange,  yellow,  8cc. 
required  for  their  production  very  different  thicknesses  from 
those  which  produced  the  same  colours  in  the  other  orders:  this, 
however,  was  but  a  supposition,  improbable  in  itself,  and  repugnant 
to  a  multitude  of  facts,  which  will  be  mentioned  in  the  course  of 
this  work. 


Philosophy  of  Permanent  Colours.^  7 

it  proper  to  write  a  Mechanical  Account  of  Poisons.  We 
arc  not,  therefore,  to  wonder  that  Newton  himself  should 
have  been  misled  on  this  subject,  since  the  whole 
amount  of  chemical  knowledge  in  his  time,  had  he  pos- 
sessed it,  would,  like  an  ignis  fattius,  have  only  served 
to  light  him  astra} ;  as  in  truth  it  seems,  in  some  de- 
gree, to  have  done;  for,  after  stating  as  a  proposition, 
that  ''the  transparent  parts  of  bodies,  according  to  their 
several  sizes y  reflect  rays  of  one  colour,  and  transmit 
those  of  another,  on  the  same  grounds  that  thin  plates, 
or  bubbles,  do  reflect  those  rays,"  he  goes  on  to  men- 
tion, **  that,  by  mixing  divers  liquors,  very  odd  and 
remarkable  productions,  and  changes  of  colours,  may  be 
effected;  of  which  no  cause  can  be  more  obvious  and 
rational,  than  that  the  saline  corpuscles  of  one  liquor, 
do  variously  act  upon,  and  unite  with,  the  tinging  cor- 
puscles of  another,  so  as  to  make  them  swell  or  shrink 
(whereby  not  only  their  bulk,  but  their  density  also, 
may  be  changed),  or  to  divide  them  into  smaller  cor- 
puscles (whereby  a  coloured  liquor  may  become  trans- 
parent), or  to  make  many  of  them  associate  into  one 
cluster,  whereby  two  transparent  liquors  may  compose 
a  coloured  one:"  and  laying  it  down  as  a  proposition, 
that  "  the  bigness  of  the  component  parts  of  natural  bo- 
dies, may  be  conjectured  by  their  colours,"  he  endea- 
vours, among  other  things,  to  explain  why  the  syrup 
of  violets,  "  by  acid  liquors,  turns  red,  and,  by  urinous 
and  alkalizate,  turns  green;"  and  for  this  purpose,  he 
supposes,  that  *'  it  is  the  nature  of  acids  to  dissolve  or 
attenuate,  and  of  alkalies  to  precipitate  or  incrassate;" 
a  supposition,  which,  as  acids  and  alkalies  are  chemical 
agents,^  is  not  true  of  either  of  them,  in  the  sense  in 

*  When  acids  "  dissolve  or  attenuate,"  it  is  by  combining  and 
forming  a  new  compound  with  the  matter  so  dissolved  or  attenuat- 


8  '    Philosophy  of  Permanent  Colours, 

which  Sir  Isaac  Newton  appears  to  have  understood  it; 
though,  in  anotlier  sense,  it  is  partly  true  and  partly 
false  of  both;  since  both  are  capable  of  dissolving  a 
great  variety  of  substances,  and  when  a  substance  is 
dissolved  by  either,  it  will  most  commonly  be  decom- 
posed and  precipitated  by  the  other:  but  certainly  the 
effect  of  coagulating,  or  incrassating,  which  he  ascribes 
to  alkalies,  is  much  more  frequently  produced  by  acids; 
though  nothing  like  it  is  produced  in  any  of  the  changes 
of  colour,  which  they  occasion  to  the  syrup  of  violets. 
It  must  be  also  observed,  that  Sir  Isaac  Newton  has 
himself  admitted,  that  what  he  calls  **  fat,  sulphureous, 
unctuous  bodies,"  possess  refractive  powers  '*  two  or 
three  times  greater,  in  respect  of  their  densities,  than 
the  refractive  powers  of  other  substances,  in  respect  of 
their's;"  an  admission,  which  seems  incompatible  with 
the  conclusion  which  he  almost  immediately  after  draws, 
**that  nothing  more  is  requisite  for  producing  all  the 
colours  of  natural  bodies,  than  the  several  sizes  and 
densities  of  their  parts."* 

ed;  and  when  alkalies  "  precipitate  or  incrassate,*'  they  always 
produce  decompositions,  and  new  compounds,  which  are  totally 
foreign  to  those  mechanical  effects  by  which  Sir  Isaac  Newton  in- 
tended to  explain  the  changes  of  colour  in  question. 

*  Since  my  objections  to  this  part  of  Sir  Isaac  Newton's  doc- 
trine were  published,  Dr.  Young,  in  the  first  volume  of  his  Lec- 
tures on  Natural  Philosophy,  p.  469,  has  delivered  the  following 
obseryations  respecting  the  Newtonian  theary  of  the  colours  of  na- 
tural bodies,  viz. 

«  Sir  Isaac  Newton  supposes  the  colours  of  natural  bodies  in 
general,  to  be  similar  to  these  colours  of  their  plates,  and  to  be 
governed  by  the  magnitude  of  their  particles.  If  this  opinion  were 
unhxrsally  true,  we  might  always  separate  the  colours  of  natural 
bodies  by  refraction  into  a  number  of  different  portions,  with  dark 
spaces  intervening;  for  every  part  of  a  thin  plate,  which  exhibits 
the  appearance  of  colour,  affords  such  a  divided  spectrum,  when 
viewed  through  a  prism.  There  are  accordingly  many  natural  co- 


Philosophy  of  Permanent  Colours.  9 

In  thus  extending  and  applying  his  conclusions,  re- 
specting the  transient  colours  of  pellucid  plates  and 
bubbles,  to  the  permanent  colours  of  all  natural  bodies, 
Sir  Isaac  Newton  appears  to  have  been  influenced  sole- 
ly by  analogy;  he  having  made  no  experiment,  or  ob- 
servation, which  would  justify  this  extension.  But  in 
the  year  1765,  Mr.  Edward  Hussey  Delaval,  F.  R.  S. 
endeavoured  to  supply  this  omission,  by  communicating 
some  experiments,  and  observations,  on  the  agreement 
between  the  specific  gravities  of  the  several  metals,  and 
their  colours,  when  united  to  glass,  as  well  as  of  their 
other  preparations,  in  a  letter  to  the  Earl  of  Morton, 
then  president  of  the  Royal  Society:  a  communication 
for  which  the  Society  bestowed  on  him  the  annual  gold 
medal  provided  by  Sir  Godfrey  Copley.  And  though 
Mr.  Delaval,  in  this  communication,  "treats  of  the  dif- 
ference of  density,  and  the  colours  produced  by  that 
cause,"  he,  notwithstanding,  considers  these  as  con- 
nected with  "  the  colours  arising  from  a  difference  of 
the  size  of  the  colouring  particles;"  since,  **  by  sepa- 
rating the  particles  of  a  coloured  substance,  they  are 
removed  to  a  greater  distance  from  each  other,  so  as  to 
occupy  more  space,"  and,  therefore,  the  substance  so 
affected,  "  must  undergo  a  diminution  of  its  specific  gra- 
vity, at  the  same  time  that  the  size  of  its  particles  is 

lours  in  which  such  a  separation  may  be  observed;  one  of  the  most 
remarkable  of  them  is  that  of  blue  glass,  probably  coloured  with 
cobalt,  which  becomes  divided  into  seven  distinct  portions.  It 
seems,  however,  impossible  to  suppose  the  production  of  natural 
colours  perfectly  identical  with  that  of  the  colours  of  thin  plates, 
on  account  of  the  known  minuteness  of  the  particles  of  colouring 
bodies,  unless  the  refractive  density  of  their  particles  be  at  least  20 
or  30  times  as  great  as  that  of  glass  or  water;  which  is  indeed  not 
at  all  improbable  vvith  respect  to  the  ultimate  atoms  of  bodies,  but 
difficult  to  believe  with  respect  to  any  of  their  arrangements  con- 
stituting the  diversities  of  material  substances." 
Vol.  I.  B 


10  Philosophy  of  Permanent  Colours. 

lessened."  And  as  Sir  Isaac  Newton  had  inferred,  that 
the  refractive  and  reflective  powers  of  bodies,  were 
nearly  proportional  to  their  densities,  and  that  the  least 
refrangible  rays,  require  the  greatest  power  to  reflect 
them,  Mr.  Delaval  conceived,  "  that  denser  substances 
ought,  by  their  greater  reflective  power,  in  like  circum- 
stances, to  reflect  the  less  refrangible  rays;  and  that 
substances  of  less  density,  should  reflect  rays  propor- 
tionably  more  refrangible,  and  thereby  appear  of  several 
colours,  in  the  order  of  their  density."  And,  in  support 
of  this  opinion,  he  undertook  to  "  give  instances  of  na- 
tural bodies,  which  differ  from  each  other  in  density, 
though  circumstanced  alike  in  other  respects;"  and  also 
differ  "  in  colour,  in  the  same  order  as  they  do  in  den- 
sity; the  densest  being  red,  the  next  in  density  orange, 
yellow,  &c. 

*'  In  such  an  inquiry,"  says  he,  "  metallic  bodies 
seem  to  demand  bur  first  and  principal  attention,  as 
their  specific  gravities  have  been  Ascertained,  by  wtII- 
known  and  repeated  experiments."  Mr.  Delaval,  how- 
ever, must  doubtless  have  perceived,  that  metals,  in 
their  pure  simple  forms,  could  not  suit  his  purpose  of 
supporting  and  extending  the  doctrine  of  Sir  Isaac  New- 
ton, in  this  respect;  since  platina,  which  is  much  the 
heaviest  of  all  metals,  and  of  all  known  substances,  in- 
stead of  being  the  most  red^  as  upon  this  hypothesis  it 
ought  to  have  been,  is  white,  like  tin,  the  lightest  of 
metals;  and  gold,  the  heaviest  of  metals  after  platina,  is 
much  farther  removed  from  the  red  colour  than  copper, 
which  is  so  much  lighter.  And  this  is  more  remarkably 
the  case  of  quicksilver,  lead,  &c.  To  obviate  so  formi- 
dable a  difficulty,  he  thought  it  expedient  to  premise, 
that,  "  as  the  infiammahle  matter  in  the  entire  metals, 
acts  strongly  on  the  rays  of  light,  it  is  necessary  tp  cal- 
cine, or  divide  them  into  extremely  minute  particles,  in 


Philosophy  of  Permanent  Colours,  It 

order  to  examine  separately  the  action  of  the  calx,  or 
Jixed  matter,  on  the  rays  of  light."  But  here,  at  the 
very  threshold,  Mr.  Delaval  is  forced  to  suppose  the 
presence  of  what  he  calls  inflammable  matter  acting 
strongly  on  the  rays  of  light,  and  thus  producing  or 
changing  colours,  by  properties  very  different  from 
those  of  density,  and  size  or  thickness  of  particles.  I 
might  here  deny,  as,  in  truth,  I  am  very  far  from  be- 
lieving, the  existence  of  any  such  matter  in  metals, 
which,  according  to  the  new  and  prevailing  chemical 
doctrine,  are  simple  substances,  uncombined  with  any 
such  matter  as  is  here  supposed.  Admitting,  however, 
for  the  sake  of  argument,  that  phlogiston,  or  inflamma- 
ble matter,  does  exist  in  metals;  it  must  be  recollected, 
that  their  calcination  is  not  a  mere  abstraction  thereof; 
since  there  is  no  fact  in  chemistry  better  ascertained, 
than  that  every  metal  in  its  calcination  unites  with  a 
considerable  portion  of  vital  air,  or  its  basis,  the  oxy- 
gene*  of  the  modern  chemists,  and  which  (only  by  va- 

*  By  oxygene  is  meant  that  substance  which,  combined  with  and 
rendered  elastic  by  heat,  or  by  heat  and  light,  constitutes  vital  air; 
or  what  Dr.  Priestley  terms  dephlogisticated  air  (first  discovered  by 
him  in  August,  1744),  the  only  fluid  suited  for  respiration;  the 
fiabulum  vita^  without  which  the  more  perfect  animals  cannot  live, 
even  for  a  few  minutes.  But  as  the  stimulant  or  exhilarating  ef- 
fects of  this  (vital)  air  would  excite,  and  wear  out,  the  powers  of 
life  too  much  and  too  rapidly,  if  it  were  inspired  without  mixture, 
the  wise  Author  of  Nature  has  presented  it  to  us  diluted  with  near- 
ly four  times  as  much  of  a  different  air  not  respirable  by  itself,  and 
which  is  now  denominated  azote^  or  nitrogene.  These  two  airs, 
with  a  very  small  portion  of  carbonic  acid  gas,  or  fixed  air,  and 
some  accidental  or  extraneous  matters,  compose  our  common  at- 
mospheric air.  The  oxygene,  combined  with  nitrogene,  constitutes, 
according  to  their  different  proportions,  either  the  nitrous  or  nitric 
acid;  the  same  oxygene  united  to  sulphur  by  combustion,  produces 
cither  sulphureous  or  sulphuric  (vitriolic)  acid;  and,  with  other 
bases,  it  seems  to  produce  most  of  the  other  acids.  With  pure 


12  Philosophy  of  Permanent  Colours. 

nations  of  proportion)  is  capable  of  producing,  with 
particular  metals,  (and  with  other  substances),  all  the 
possible  variations  of  colour.  Of  this,  however,  Mr. 
Delaval  takes  no  account:  indeed,  when  treating  of  the 
colours  of  mercury,  he  expressly  says,  "  I  have  not  en- 
tered  into  the  consideration  of  the  air,  which  unites 
with  mercurial  colours  during  their  exposure  to  fire; 
because  it  does  not  relate  to  the  greater  or  less  division 
of  their  particles,  which  is  the  immediate  subject  of  my 
inquiry."  So  that,  by  his  own  statement,  he  has  over- 
looked (because  it  did  not  suit  his  hypothesis)  the  only 
thing  worthy  of  notice  on  this  subject;  since  the  oxides 
or  calces  of  mercury,  and,  indeed,  of  all  other  metals, 
indisputably  receive  their  various  colours  only  by  addi- 
tions, greater  or  smaller,  of  that  air  which  he  professes 
to  have  disregarded;  and  which,  as  he  declares,  has  no 
relation  to  the  greater  or  lesser  division  of  their  parti- 
cles; and  we  must  therefore  conclude,  that  the  various 
colours  assumed  by  these  calces,  under  the  circum- 
stances in  question,  do  not  result  from  any  such  divi- 
sion. 

But  though  Mr.  Delaval  inculcates  the  necessity  of 
calcining  metals,  '*  in  order  to  examine  separately  the 
action  of  their  calces  or  fixed  matter,  on  the  rays  of 
light,"  he  does  not  adduce  the  colours  which  they  as- 
sume when  so  calcined,  as  any  evidence  of  the  truth  of 
his  hypothesis;  and,  indeed,  he  might  have  perceived 
them  to  be  absolutely  incompatible  with  it,  since  the 
same  oxide,  by  diflferent  degrees  of  calcination,  exhibits 
very  great  diversities  of  colour.  But  in  order  to  obtain 
from  several  of  the  metals  such  colours  as  suited  his 

charcoal  (carbone)  it  produces  carbonic  acid  (or  fixed  air),  and 
with  inflammable  air  (hydrogene)  it  produces  water.  This  expla- 
nation may  be  useful  to  readers  not  acquainted  with  the  modern 
chemistry. 


Philosophy  of  Permanent  Colours.  13 

purpose,  he  continued  to  melt  them  with  what  he  was 
pleased  to  think  *'  a  quantity  of  the  purest  glass,"  and 
as  they,  when  more  or  less  calcined,  and  melted  or 
united  with  a  greater  or  less  portion  of  glass,  are  capa- 
ble each  of  giving  several,  and  some  of  giving  all  the 
colours,  it  could  not  be  difficult  for  him  to  find  out,  and 
assign  to  each  metal,  as  its  proper  colour,  that  which  it 
ought  to  have,  upon  his  supposition  that  the  colours  of 
metals  depended  on  their  respective  densities.  Thus, 
for  example,  iron  highly  calcined,  or  combined  with  a 
large  portion  of  the  basis  of  vital  air,  (oxygene),  gives  a 
red  colour  to  melted  glass;  and  if  the  glass  be  continued 
m  fusion,  the  (oxygene)  will  by  degrees  be  separated, 
and  in  proportion  to  its  separation,  the  colour  of  the 
glass  will  change  to  orange,  yellow,  green,  blue,  and 
white.  And  as  blue  is  the  colour  which  suits  Mr.  De- 
laval's  purpose,  he  selects  and  assigns  it  as  the  proper 
colour  of  iron,  and  the  degree  of  heat  producing  it,  as 
the  proper  one  for  manifesting  those  which  suits  him  to 
consider  as  the  true  colours  of  metals;  though  in  fact  he 
took  no  means  to  ascertain  what  this  degree  of  heat 
really  was;  and  the  effect,  or  blue  colour,  would  require 
very  different  degrees,  according  to  the  greater  or  lesser 
degree  of  calcination  which  the  iron  had  previously  un- 
dergone, or,  in  other  words,  according  to  the  quantity 
of  oxygene  previously  combined  with  it. 

Where  every  thing  is  in  this  way  assumed  or  sup- 
posed at  pleasure,  not  only  without  evidence  or  proba- 
bility, but  often  against  both,  it  must  have  been  easy 
for  Mr.  Delaval  to  give  some  plausibility  to  this  falla- 
cious hypothesis,  though  it  is  absolutely  incompatible 
with  a  multitude  of  facts. 

Mr.  Delaval  has  quoted,  from  Glauber's  Prosperity 
of  Germany  (translated  by  Packe,  1689),  some  curious 
observations  respecting  the  various  colours  produced 


14  Philosophy  of  Permanent  Colours. 

by  manganese;  and  he  adds,  as  from  his  own  know- 
ledge,  that  "  amongst  the  mmeral  substances,  none 
aiFords  a  greater  variety  of  bright  colours,  especially 
when  it  is  fused  with  nitre,  or  a  fixed  alkali;"  ef  these 
he  instances  a  yellow,  produced  by  dissolving  manga- 
nese in  a  weak  spirit,  together  with  a  green,  blue,  pur- 
ple, and  red,  produced  by  water  poured  on  it;  in  the 
first  instance  cold,  and  in  the  others  warm,  then  warm- 
er, hot,  and  boiling;  all  which  colours  he  ascribes  to 
different  degrees  of  solution,  or  attenuation,  of  the  par- 
ticles of  manganese.  But  in  truth  this  and  other  metal- 
lic calces  or  oxides,  had  he  properly  attended  to  their 
various  changes  of  colour,  might  have  shown  him  both 
the  fallacy  of  his  own  hypothesis,  and  the  road  to  a 
better.  Manganese  is  the  oxide  or  calx  of  a  metal  which 
has  so  strong  an  attraction  for  the  basis  of  vital  air,  that 
one  of  the  most  excellent  of  chemists,  Berthollet,  says, 
we  may  safely  consider  the  whole  of  what  exists  in 
nature  to  be  as  in  a  state  of  oxidation,  or  combination 
with  oxygene:  when  saturated  therewith,  I  mean  with 
the  basis  of  vital  air,  it  is  black;  and  if  it  be  diluted  or 
diffused  in  melted  glass,  it  becomes  purple,  or  red;  and 
as  the  vital  air  diminishes  by  burning  with  the  coaly 
impurities,  (which  it  is  employed  to  destroy),  in  glass, 
it  gradually  loses  its  power  of  producing  colours,  and 
leaves  the  glass  colourless;  though  its  colours  may  be 
restored  by  nitre,  or  any  thing  affording  pure  air.  The 
different  solutions  of  manganese,  mentioned  by  Glauber, 
and  others,  undergo  their  various  changes  of  colour, 
in  consequence  of  a  gradual  separation  or  diminution 
of  their  oxygene;  and  that  this  is  what  manganese  pos- 
sesses, and  what  it  loses,  in  these  operations,  is  well 
known  to  all  who  are  acquainted  with  the  later  chemical 
discoveries.  I  have  already  noticed  the  various  colours 
assumed  by  the  oxides  or  calces  of  iron,  when  com- 


Philosophy  of  Permanent  Colours,  15 

bined  with  different  portions  of  the  same  air,  or  its 
basis,  the  oxygene,  which  are  indeed  so  many  and  va- 
rious, that  I  remember  having  been  told  by  the  late 
Mr.  Wedgwood,  that  all  the  diversified  colours  applied 
to  his  pottery,  were  produced  by  the  oxides  of  this  sin- 
gle metal;  which  must  have  been  all  of  very  nearly  the 
same  specific  gravity,  and  they  were  besides,  in  these 
cases,  combined  or  melted  with  glass,  the  substance 
which  Mr.  Delaval  thought  proper  to  choose,  as  being 
of  all  others  the  best,  for  exhibiting  what  he  was  pleased 
to  think  the  true  colours  of  metals.  In  like  manner  the 
oxides  or  calces  of  mercury,  lead,  copper,  &c.  assume 
each  a  variety  of  colours,  by  combinations  with  diffe- 
rent portions  of  oxygene,  without  any  thing  like  a  cor- 
respondent variation  of  density,  or  of  specific  gravity 
in  any  of  them.  Of  this  Mr.  Delaval  appears  to  have 
been  sensible,  at  least  in  the  instance  of  lead,  and  he 
endeavours  to  obviate  the  evidence  which  it  affords 
against  his  theory,  by  ascribing  the  various  colours  of 
that  metal  to  its  "  imperfection,"  which  he  is  pleased 
to  suppose,  without  any,  and  against  every,  kind  of  proof 
and  probability:  and  then  he  proceeds  to  say,  "  it  is 
probable  that,  during  the  calcination,  lead  receives  a 
small  portion  of  phlogiston,  as  well  as  of  air;  for  the 
affinity  between  the  earth  of  this  metal  and  inflammable 
matter  is  very  great,  as  appears  from  the  readiness  with 
which  its  solutions  and  calces  unite  with  phlogistic  va- 
pours." "  The  effect  of  such  an  union,"  he  adds, 
"  must  probably  be  a  change  of  colour  from  orange  to 
red;  for  Sir  Isaac  Newton  has  shown,  that  bodies  reflect 
more  strongly  in  proportion  as  they  possess  more  phlo- 
giston, and  that  the  less  refrangible  colours  require 
greater  power  to  reflect  them."  Here  we  have  another 
gratuitous  and  strange  supposition  of  an  accession  or 
combination  of  phlogiston  with  lead  in  calcination:  I 


16  Philosophy  of  Permanent  Colours, 

say  strange,  because  those  of  the  adherents  of  phlogis- 
ton who  yet  continue  to  believe  its  existence  in  metals, 
have  constantly  supposed  that,  in  calcination,  while  they 
received  air,  they  lost^  instead  of  gainings  infiammable 
matter.  But  were  this  extravagant  supposition  to  be 
admitted  as  a  cause  of  the  changes  of  colour  in  metals, 
how  can  it  be  reconciled  to  any  hypothesis  which  makes 
their  colours  depend  on  their  respective  densities?  In- 
deed, if  the  effects  which  Sir  Isaac  Newton  supposes 
phlogiston  to  produce  on  colours  were  real,  and  if  phlo- 
giston existed  in  them,  as  he  and  Mr.  Delaval  imagined, 
it  would  be  difficult  to  conceive  why  all  metals  are  not 
red,  or  more  inclined  to  redness,  than  their  calces  or 
oxides.  But  enough,  perhaps  too  much,  has  been  said, 
to  refute  Mr.  Delaval's  hypothesis,  so  far  as  it  relates 
to  the  colours  of  metals.  Unfortunately,  however,  for 
my  readers,  as  well  as  for  myself,  he  has  thought  pro- 
per, in  a  larger  work,*  published  some  time  since,  to 
extend  the  same  hypothesis  to  the  colours  of  animal  and 
vegetable  substances;  and  has  endeavoured  to  confirm 
and  illustrate  Sir  Isaac  Newton's  ideas  on  this  subject, 
by  a  variety  of  experiments,  which  are  represented  as 
instances  of  changes  of  colour  produced  in  these  sub- 
stances, by  an  increase  or  diminution  in  the  sizes  of 
their  particles:  I  am,  therefore,  compelled  reluctantly 
to  extend  my  own  observations  a  little  farther  on  this 
subject;  and  I  must  begin  by  complaining  of  a  continu- 
ance of  gratuitous  and  fallacious  suppositions^  similar  to 
those  which  I  have  before  had  occasion  to  notice;  for 
when,  in  operating  upon,  or  with  different  matters,  he 
professes  either  to  increase  or  diminish  the  sizes  of 
their  particles,  and  to  do  nothing  more^  (to  show  that 

*  Experimental  Enquiry  into  tlie  Cause  of  the  Permanent  Co- 
lours of  Opake  Bodies.  4to. 


Philosophy  of  Permanent  Colours,  17 

the  changes  of  colour  produced  in  them,  accord  with 
the  thicknesses  stated  in  the  table  of  Sir  Isaac  Newton,) 
instead  of  choosing  and  employing  mechanical  means, 
which  alone  are  suited  to  produce  these,  and  only  these 
effects,  he  has  recourse  to  mere  chemical  agents,  whose 
action  in  the  ways  which  he  supposes,  must  have  been 
always  doubtful  at  least,  though  their  powers  of  pro- 
ducing other,  and  very  different  effects  from  any  sup- 
posed by  him,  is  most  certain.  Mr.  Delaval,  however, 
adopting  Sir  Isaac  Newton's   supposition,  that  acids 
always  attenuate,  and  alkalies  always  incrassate,  pre- 
pared what  he  considered  as  a  dissolving  or  attenuating 
liquor;  which  "  consisted  of  water,  with  about  an  eigh- 
tieth part  of  aqua  fortis:  and  when  he  wanted  to  lessen 
the  dissolving  force  of  this  liquor,  instead  of  weakening 
it  by  the  addition  of  water  (which  would  certainly  have 
been  the  most  obvious  and  unexceptionable  expedient), 
he  chose  to  do  it,  as  he  says,  by  adding  "  a  small  quan- 
tity of  a  solution  of  potash,  or  some  other  alkaline  li- 
quor;" and  thereby  produced  a  new  composition,  the 
effects  of  which  must,  in   many  cases,  prove  different 
from  those  of  a  mere  diminution  of  the  supposed  dis- 
solving power  of  the  former  liquor.  And  on  the  other 
hand,  when  he  wanted  to  increase  the  force  of  his  acid 
liquor,  instead  of  doing  it  by  a  farther  addition  of  aqua 
fortis  (obviously  the  most  proper  expedient),  he  recurs 
to  an  addition  of  oil  of  vitriol;  an  acid  possessing  very- 
different  properties,  and  producing  very  different  effects, 
on  a  great  variety  of  substances,  and  particularly  on 
colouring  matters;  of  which  I  could  allege  hundreds  of 
instances,  but  shall  content  myself  with  only  mention- 
ing, that  the  strongest  and  most  concentrated  oil  of  vi- 
triol (used  to  dissolve  indigo  for  dyeing  the  Saxon  blue, 
&c.)  does  not  destroy,  or  even  weaken,  its  blue  colour, 
though  a  diluted  nitric  acid,  or  aqua  fortis,  will  wholly 
Vol.  I.  C 


18  Philosophy  of  Permanent  Colours, 

destroy  it,  and  convert  the   indigo  to  a  dirty  brovvii 
mass,  of  no  use  whatever. 

Having  thus  assumed,  that  acids  attenuate,  and  do 
nothing  but  attenuate,  the  particles  of  colouring  matter; 
that  alkalies  incrassate,  and  doing  nothing  butincrassate, 
the  same  particles;  that  by  adding  an  alkali  to  his  mix- 
ture of  aqua  fortis  and  water,   he  weakens,  and  only 
weakens,  its  attenuating  force  on  one  hand;  and  that  on 
the  other  he  increases,  and  only  increases  it,  by  an  ad- 
dition of  vitriolic  acid;   he  next  provides  himself  with 
so  much  of  Sir  Isaac  Newton's  table  before  mentioned 
as  suits  his  purpose,  by  transcribing  the  diiferent  co- 
lours of  the  three  first  orders,  and  the  different  thick- 
nesses of  air,  water,  and  glass,  supposed  to  produce 
each  of  these  colours,  one  after  the  other;  and  thus 
"•equipped^  he  proceeds  to  make  experiments  upon  red 
infusions,  of  certain  vegetables,  and  generally  finds,  that 
with  his  acid  liquor,  the  colour  continues  red;  that,  with 
the  addition  of  oil  of  vitriol,  to  attenuate  farther,  (as  he 
supposes)  it  becomes  yellow;  and  that  if,  instead  of  oil 
of  vitriol,  he  adds  an  alkali,  to  incrassate,  it  becomes  a 
purple.  Now  it  so  happens,  that  though  all  the  other 
colours  are  repeated  in  more  than  one  order,  purple  is 
marked  but  once  in  Sir  Isaac  Newton's  table,  and  then 
it  is  placed  as  the  first  colour  of  what  he  terms  the  third 
order;  and  if  the  red  and  yellow,  from  which  the  purple 
in  question  had  proceeded,  were  supposed  to  be  of  the 
same  order  (as  might  be  expected),  then  the  production 
of  this  purple  ought,  upon  Mr.  Delaval's  theory,  to  re- 
sult not  from  incrassation,  but  from  attenuation;  since 
the  particles  of  it  are  stated  to  be  nearly  one  third  less 
in  size,  than  the  particles  of  the  red,  and  nearly  one 
fourth  smaller  than  those  of  the  yellow  of  the  same 
order:  but  such  is  the  happy  arrangement  ef  this  table, 
and  of  the  several  orders  of  colours,  that,  by  supposing 


Philosophy  of  Permanent  Colours*  19 

the  red  in  this  instance  to  be  the  red  of  the  second  order, 
he  finds  a  purple  below  it  in  the  third,  with  only  one , 
intervening  colour,  and  a  yellow  at  the  same  distance  , 
above;  and  by  these  leaps,  he  reconciles  the  appearances 
to  the  theory.  Indeed,  as  the  second,  or  middle  order 
in  the  table,  contains  all  the  different  colours,  and  as, 
excepting  one,  they  are  all  repeated  in  the  first  order, 
which  is  above;  and  also  in  the  third,  which  is  below; 
hardly  any  change  of  colour  can  happen,  which  may 
not  be  made  to  accord  with  Mr.  Delaval's  hypothesis, 
he  being  always  allowed  to  suppose  each  original  or 
primitive  colour  to  belong  to  that  order  which  may  be 
most  convenient  for  his  purpose;  though,  in  truth,  the 
very  admission  of  different  orders  or  repetitions  of  the 
same  colours,  produced  repeatedly  by  and  at  different 
thicknesses,  or  sizes,  either  of  particles  or  plates  of 
matter,  is  of  itself  a  proof  (as  I  have  before  observed) 
that  such  colours  do  not  depend  on  any  particular  thick- 
ness of  plates  or  size  of  particles.* 

*  When  Mr.  Delaval,  on  every  occasion,  allots  each  particular 
colour  to  some  one  order,  exclusively  of  the  rest,  it  would  seem 
reasonable  to  expect,  that  he  should  justify  this  allotment  by  some- 
thing besides  his  own  convenience,  and  particularly  that  he  should 
prove  that  the  red,  for  instance,  which  he  places  in  the  second 
order,  exceeds  that  of  the  first  order,  in  the  density  and  size  of  its 
particles,  exactly  in  the  same  proportion  as  1 8-|  exceeds  9;  and  that 
the  red  which  he  places  in  the  third  order,  exceeds  that  of  the  se- 
cond exactly  in  the  proportion  of  29  to  18^:  and  that  the  other  co- 
lours of  the  several  orders,  diifer  from  each  other  likewise,  accor- 
ding to  the  proportions  stated  to  be  necessary  for  their  production, 
in  the  table  which  he  has  adopted  from  Sir  Isaac  Newton.  Before 
this  division  of  colours  into  orders,  and  the  hypothesis  connected 
with  it,  can  be  admitted  to  have  any  other  than  an  imaginary  foun- 
dation, it  ought  to  be  proved,  that  all  the  known  reds,  differ  from 
each  other  in  respect  to  the  densities  and  sizes  ot  their  particles, 
exactly  according  to  the  before-mentioned  proportions;  and  so  of  the 
oranges,  yellows,  Sec.  since,  in  every  case,  the  slightest  deviation 


2&  Philosophy  of  Permanent  Colours. 

I  am  far  from  thinking  that  Mr.  Delaval  has  always 
chosen  the  matters,  most  proper  for  fair  experiments, 
or  that  the  experiments  themselves,  even  on  his  own 
principles,  were  well  calculated  to  ascertain  the  truth. 
But  such  as  they  are,  I  can  readily  point  out  several, 
which,  on  his  own  improbable,  or  rather  impossible 
supposition,  of  mechanical  attenuation  or  incrassation^ 
and  nothing  else,  by  chemical  agents,  cannot  be  recon- 
ciled to  his  theory,  even  by  the  assistance  of  Sir  Isaac 
Newton's  convenient  table.  The  green  leaves  of  the 
anil  (indigofera)  and  glastrum,  he  says  *'  being  long 
steeped  in  water,  their  parts  are  dissolved  into  a  blue 
substance,  which  is  indigo  and  woad."  Now  the  truth 
is,  that  the  blue  arising  from  these  vegetables  is  not  the 
result  of  any  dissolution^  but  of  an  absorption  of  pure 
air,  during  the  fermentation  which  they  undergo;  and 
this  colour  does  not  manifest  itself,  until  there  is  a  be- 
ginning aggregation  and  concretion  of  its  matter,  into 
larger  particles,  which  becoming  denser,  as  well  as 
larger,  sink  down  to  the  bottom,  leaving  the  water 
nearly  colourless.  So  that  here  the  change  from  green 
to  blue,  is  manifestly  accompanied  with  an  increase, 
both  in  the  size  and  density  of  the  coloured  particles, 
which  is  absolutely  incompatible  with  Mr.  DelavaPs 
hypothesis;  since,  according  to  the  table  in  question, 
every  change  of  colour  from  green  to  blue  is  the  effect 
of  a  diminution,  not  an  increase,  in  the  size  and  density 
of  its  particles.  When  the  indigo  itself  (formed  into  dry 
masses)  is  to  be  dissolved  for  dyeing,  by  the  combined 

from  the  thickness  or  size  of  particles,  stated  as  essential  to  the 
production  of  a  particular  colour,  ought  to  occasion  the  appearance 
of  that  colour,  which  is  next  in  the  series  above  or  below.  But 
nothing  like  this  is  any  where  attempted,  nor  is  there  any  thing 
accessible  to  human  observation,  which  could  in  any  degree  justify 
the  attempt. 


Philosophy  of  Permanent  Colours,  21 

action  of  caustic  alkalies,  and  of  particular  chemical 
attractions,  or  vegetable  ferments,  the  sohition,  though 
manifestly  attended  with  a  division  or  diminution  of  the 
coloured  particles  (as  well  as  a  loss  of  the  air  absorbed 
during  the  first  process)  becomes  green,  contrary  to  the 
table  and  hypothesis  in  question;  and  in  this  state,  it  is 
applied  by  the  dyers  to  wool,  and  other  substances,  to 
be  dyed;  and  these,  when  first  taken  out  and  exposed 
to  the  air,  appear  green;  but  by  absorbing,  and  uniting 
with  a  portion  of  oxygene,  they  immediately  become 
blue,  and  in  doing  so,  the  divided  particles  again  con- 
crete into  larger  ones,  as  must  be  evident,  among  other 
proofs,  from  this,  that  the  surface  of  the  indigo  liquor, 
on  which  the  air  has  an  immediate  action,  is  from  that 
cause  always  blue;  and  if  we  skim  off  this  blue  matter, 
(which  is  nothing  but  indigo  revived)  it  will  be  found 
impossible  to  make  it  enter  the  pores  of  any  substance, 
so  as  to  dye  a  permanent  colour  therewith;  because  the 
particles  having  regained  their  proper  portion  of  pure 
air,  or  its  basis,  are  no  longer  sufficiently  divided  and 
dissolved  for  that  purpose;  so  that  in  all  these  cases,  the 
matter  of  indigo  becomes  more  dense,  and  its  particles 
larger,  in  passing  from  green,  to  the  more  refrangible 
colour,  blue;  and  the  contrary,  in  passing  from  blue  to 
the  less  refrangible  colour,  green.  And  this  is  also  the 
case,  when  the  infusions  of  rhubarb,  turmeric,  &C.  are 
made  *'  to  descend  (as  he  expresses  it)  from  yellow  to 
orange  and  red,"  "  by  the  addition  of  an  alkali,"  which, 
whatever  he  may  imagine  to  the  contrary,  dissolves  these 
colouring  matters  more  powerfully  than  any  acid.  Si- 
milar objections  occur,  in  opposition  to  the  instances 
which  Mr  Delaval  alleges,  respecting  "  the  changes  of 
colour  which  animal  substances  undergo."  Among  these, 
<?.  g,  he  observes,  that  cow's  milk,  boiled  up  with  an 
alkali,  changes  from  white  to  yellow,  orange,  and  red; 
and,  as  usual,  he  gratuitously  supposes,  that,  in  produc- 


22  Philosophy  of  Permanent  Colours. 

ing  these  changes,  it  acts  by  incrassating,  or  coagulating 
the  milk;  though  if,  contrary  to  all  probability,  alkalies 
were  able  to  do  this,  we  have  no  reason  to  conclude 
that  such  coagulation  would  render  the  milk  either  yel- 
low, orange,  or  red,  because  no  such  colours  appear 
when  it  really  is  coagulated  by  acids,  &c.  as  in  the 
making  of  curds  and  cheese.  But  surely  it  cannot  be 
necessary  for  me,  seriously  to  combat  such  chimeras 
any  longer.  The  common  sense  and  experience  of  man- 
kind, if  fairly  consulted,  will  condemn  and  revolt  at  the 
idea  of  making  the  colours  of  bodies  depend  on  their 
weight,  or  the  sizes  of  their  particles;  for  it  certainly 
never  has  been  observed,  that  the  heaviest  substances 
were  red,  or  the  lightest  violet-coloured,  or  that  bodies 
equally  heavy  were  all  of  the  same  colour.  Different 
parcels  of  indigo,  for  instance,  vary  extremely  as  to 
specific  gravity,  without  any  variation  of  colour;  a  fact 
which  is  not  only  at  variance  with  Mr.  Delaval's  hypo- 
thesis, but  which  renders  it  easy  to  find  samples  of  in- 
digo, of  exactly  the  same  specific  gravity  as  the  colour- 
ing matter  of  cochineal  (exhibited  in  what  is  called 
cannine,)  which  of  all  colours  is  the  farthest  removed 
from  that  of  indigo:  and  if  Mr.  Delaval  should  allege, 
that,  though  agreeing  in  weight,  they  differ  as  to  the 
sizes  of  their  respective  particles,  let  him  correct  this 
diflference  by  the  only  means  suited  to  do  it,  without 
doing  more;  I  mean  by  simple  mechanical  division,  or 
grinding.  Let  this  be  employed  upon  cither  of  the  sub. 
stances  in  question,  whose  particles  he  may  suppose 
too  large,  as  long  as  he  shall  think  proper,  and  let  us 
then  see  whether  he  can  thereby  render  the  colour  of 
indigo  red,  or  that  of  cochineal  blue  or  violet. 

Should  what  I  have  said  on  this  subject  prove  insuf- 
ficient to  convince  any  one  of  my  readers,  I  only  beg 
that  he  \y\\\  follow  me,  with  a  mind  open  to  conviction, 
through  the  various  instances,  which,  for  other  pur- 


Philosophy  of  Permanent  Colou7's.  23 

poses,  I  shall  have  occasion  to  state  hereafter,  of  colours 
produced,  or  changed  by  means,  and  in  ways,  that  are 
wholly  irrcconcileable  to  the  theory  in  question,  and  I 
persuade  myself  that  his  doubts  and  difficulties  will  be 
effectually  removed,  so  far  as  they  may  relate  to  the 
truth  or  fallacy  of  Mr.  Delaval's  hypothesis,  of  which  I 
mean  hereafter  to  be  silent,  because  I  dislike  even  the 
appearance  of  contention;  nor  would  I  have  so  long  de- 
tained my  readers  on  this  subject,  but  from  a  conviction 
of  the  truth  of  what  I  have  written,  and  of  the  expedi- 
ency of  refuting  an  hypothesis,  incompatible  with  a 
considerable  part  of  what  I  am  about  to  offer  to  the 
public;  an  hypothesis  which  the  name  and  authority  of 
Sir  Isaac  Newton  had  pre-eminently  sanctioned;  and 
which  the  learning  and  talents  of  Mr.  Delaval  had  ren- 
dered so  plausible,  that  it  is,  I  believe,  generally  con- 
sidered as  true,  in  this  and  other  countries.* 

Having  shown,  that  the  permanent  colours  of  diffe- 
rent objects  do  not  arise  from  their  densities,  or  the 
sizes  of  their  particles,  it  becomes  me  to  state  such 
facts  and  observations,  as  seem  best  suited  to  throw 
light  upon  this  obscure  and  interesting  subject. 

Sir  Isaac  Newton  having  found  that  inflammable  sub- 
stances, possessed  greater  refractive  powers  than  others, 
in  proportion  to  their  densities,  says,  in  his  second  Book 
of  Optics,  that  ''  it  seems  rational  to  attribute  the  re- 
fractive power  of  all  bodies,  chiefly,  if  not  wholly,  to 
the  sulphureous  parts  with  which  they  abound;  for, 
adds  he,  it  is  probable  that  all  bodies  abound  more  or 
less  with  sulphurs;"  a  term  by  which  he  intended  to 
distinguish  inflammable  matters  generally.  And  this 
great  man  having  also  concluded,  that  the  permanent 
colours  of  natural  bodies,  were  analogous  to  the  colours 

*  Such  was  the  fact  in  1794,  when  this  was  first  published. 


24  Philosophy  of  Permanent  Colours. 

produced  by  the  refractions  of  thin,  colourless,  transpa- 
rent plates,  &c.  chemists  were  generally  induced  to 
make  all  colour  depend  on  the  principle  of  inflamma- 
bility or  phlogiston,  which  was  supposed  to  exist  in  all 
metals,  and  many  other  substances;  and  where  the  total 
want  of  inflammability  was  manifest,  they  confounded 
thisy  with  the  matter  of  heat  and  of  light;  to  which  they 
ascribed  the  power  of  phlogisticating  other  substances, 
and  of  thereby  producing  or  changing  their  colours:  a 
species  of  confusion  suited  only  to  cover  and  perpetuate 
ignorance;  since  every  single  colour  is  found  to  belong 
both  to  combustible  and  incombustible  substances,  and 
to  neither  exclusively.  The  combustible  diamond,  which 
Sir  Isaac  Newton  conjectured  to  be  **  an  unctuous  sub- 
stance coagulated,"  is  found  to  be  of  almost  all  the 
different  colours;  whilst  other  gems,  though  of  similar 
colours,  are  all  incombustible.  Combustible  indigo,  and 
incombustible  smalt,  are  both  blue;  combustible  ver- 
milion and  incombustible  minium  are  both  red;  com- 
bustible gamboge  is  yellow,  and  so  are  certain  incom- 
bustible oxides  of  lead,  iron,  and  mercury.  But  since 
the  existence  of  phlogiston  in  metals,  &c.  has  been  de- 
nied by  the  pneumatic  chemists,  they  have  in  most 
cases,  attributed  the  origin  and  changes  of  colours,  to 
the  application  or  combination  of  diflferent  airs  or  gases, 
and  particularly  oxygene  in  different  proportions;  and 
it  has  been  supposed  that  these  gases  possessed  con- 
siderable refractive  powers,  and  were  thereby  ena- 
bled to  produce  effects  on  colours,  like  those  which 
the  followers  of  Stahl  had  imputed  to  phlogiston:  and 
M.  BerthoUet,  in  his  recent  work  on  the  Elements  of 
Dyeing,  intimates,  that  "  many  important  observations 
still  remain  for  those  who  would  follow  the  steps  of 
that  great  man,  (Sir  Isaac  Newton),  and  compare  the 
refracting  powers  of  the  diflferent  gases,  and  other  sub- 


Philosophy  of  Permanent  Colours.  25 

stances,  the  constituent  principles  of  which  are  now 
known."* 

Though  it  be  true  that  the  prism,  and  other  transparent 
colourless  substances,  in  different  forms,  show  us  the 
different  colours  of  the  several  rays  of  light,  by  sepa- 
rating them  from  each  other,  in  consequence  of  their 
greater  or  lesser  refrangibility,  or  disposition  to  be 
"  turned  out  of  their  vvay,  in  passing  out  of  one  trans- 
parent body  or  medium  into  another,"  (which  may  de- 
pend upon  differences  in  their  sizes,  densities,  or  velo- 
cities,) yet  th*;^  permanent  colours  of  different  bodies,  or 
substances,  are  not,  as  1  believe,  produced  by  mere  re* 

*  Ten  years  after  my  first  edition  of  this  volume  was  published, 
M.  Berthollet  (assisted  by  his  son,  lately  deceased,  and  too  soon 
for  the  interests  of  science)  favoured  the  public  with  an  improved 
edition  of  the  Elemens  de  Teinture,  in  which  (at  page  33,  of  the 
first  volume)  he  intimates,  that  it  was  his  intention,  by  the  words 
just  quoted,  to  express  some  doubt  of  the  correctness  of  this  part 
of  Sir  Isaac  Newton's  doctrine;  and  he  adds,  "  depuis  lors  Bancroft 
lui  a  oppose  un  grand  nombre  de  faits.  Nous  nous  servirons  de  se» 
diffe rentes  observations,  dans  la  discussion  que  nous  n'allons  entre- 
prendre,  que  dans  la  vue  d'appeler  sur  cet  objet  interessant,  Tat- 
tention  de  ceux  qui  peuvent  suivre  les  traces  de  J\''ewtonV  He 
then  proceeds  through  nearly  twenty  pages  to  repeat  the  facts  and 
arguments  which  I  had  employed  on  this  subject,  and  to  adduce 
other  facts  and  arguments  in  their  support,  from  all  which  he  con- 
cludes, nearly  as  I  had  done,  "  qu'il  ne  faut  point  confbndre  les 
couleurs  fugitives  qui  sont  produites  par  la  reflexion  des  lames, 
et  qui  suivent  les  loix  determinees  par  Newton,  avec  les  couleurs 
qui  se  conservent  malgre  les  changemens  de  densite  et  d*epais- 
seur.  Celles-ci  nous  paraissent  tenir  a  des  proprietes,  ou  Taffinite 
particuliere  pour  les  difllerents  rayons  de  la  lumiere,  a  une  influ- 
ence qui  resiste  a  celle  des  dimensions  et  de  la  densite;  si  nous 
examinons  les  faits,  nous  apercevons  que  Toxigene  condense  exerce 
un  grand  pouvoir  dans  cette  espece  d'affinite:  une  proportion  un 
peu  plus  on  un  peu  moins  grande,  qui  affecte  d*une  maniere  insen* 
sible  la  pesanteur  specifique  des  oxides  metalliques,  y  produit  de 
grands  changements  de  couleurs,"  &c. 

Vol.  I.  D 


26  Philosophy  of  Permanent  Colours. 

fraction^  and  Sir  Isaac  Newton  must  have  been  misled 
by  analogy  when  he  extended  his  discoveries  and  con- 
clusions respecting  the  transient  colours  resulting  from 
the  refractions  of  light,  by  pellucid  colourless  substances, 
to  the  permanent  colours  of  various  kinds  of  matter; 
since  the  latter  evidently  depend  on  other  properties, 
which  determine,  or  occasion  the  reflection  or  transmis- 
sion of  some  particular  sort  or  sorts  of  rays,  and  an 
absorption  or  disappearance  of  the  rest;  and  these  I  con- 
ceive to  be  certain  affinities^  or  elective  attractions^  ex- 
isting in  or  between  the  differently  coloured  matters 
and  the  particular  sorts  or  rays  of  light  so  absorbed  or 
made  latent;  and  of  which  many  instances  and  proofs 
will,  I  think,  be  found  in  the  subsequent  parts  of  this 
work. 

Next  after  the  diamond  and  amber,  we  find  that  spirit 
of  turpentine,  linseed  oil,  olive  oil,  camphor  and  alco- 
hol, or  rectified  spirit  of  wine,  possess  greater  refracting 
powers,  in  proportion  to  their  respective  densities,  than 
any  of  the  other  substances  contained  in  Sir  Isaac  New- 
ton's table,  and  yet  they  are  all  permanently  destitute  of 
colour;  n  fact  which  does  not  seem  to  indicate  any  con- 
nexion between  the  refractive  power  of  a  substance  and 
its  natural  permanent  colour.  Nothing  seems  to  act  so 
powerfully  and  extensively  in  producing  and  changing 
those  affinities,  or  elective  attractions,  from  which  the 
permanent  colours  of  different  substances  arise,  as  pure 
vital  air,  or  its  basis,  the  oxygene;  which,  indeed,  seems 
to  owe  its  elastic,  or  aerial  form,  to  a  portion  of  light 
as  well  as  heat.  Scheele  demonstrated  that  gold,  silver, 
&c.  were  revived  from  their  oxides  by  the  contact  of 
light;  and  M.  Berthollet  has  proved,  that,  in  producing 
this  effect,  the  light  occasions  a  separation  of  oxygene, 
in  the  form  of  pure  vital  air.  Light  also  separates  oxy- 


Philosophy  of  Permanent  Colours.  27 

gene  from  various  other  substances,  to  which  it  would 
otherwise  remain  united,  under  great  degrees  of  heat. 

We  are  at  this  time  well  acquainted  with  the  con- 
stituent parts  of  the  acid  of  nitre:  it  undeniably  consists 
of  nitrogene  or  azote,  rendered  acid  by  its  combination 
with  a  certain  portion  of  oxygene,  or  the  basis  of  vital 
air.  When  these  are  combined  in  a  certain  proportion, 
the  acid  or  compound  is  colourless,  as  we  see  it  in  aqua 
fortis,  or  nitric  acid:  but  if  this  colourless  acid,  in  a 
transparent  glass  vessel,  partly  filled^  be  exposed  to  the 
rays  of  the  sun,  or  the  light  of  a  fire,  an  alteration  will 
take  place  in  the  proportion  of  its  ingredients;  since  the 
light  will  combine  with  a  part  of  the  oxygene,  and  cause 
it  to  become  elastic  and  fly  off,  and  the  nitrogene  will 
consequently  predominate  in  the  remainder;  which,  be- 
coming nitrous  add,  merely  in  consequence  of  this  pre- 
dominance, will  assume  first  a  yellow,  then  an  orange, 
and  afterwards  a  high  vivid  aurora,  and  even  a  red 
colour,  intensely  afiecting  the  sight.  But  if  the  glass 
vessel  containing  the  colourless  nitric  acid,  w^ere  com- 
pletely filled  with  it,  and  closely  stopped,  no  such  change 
of  colour  would  take  place  by  any  degree  of  exposure 
to  the  sun's  rays  or  other  light;  because,  in  this  case, 
there  would  be  no  sufficient  space  or  room  to  allow  of 
a  separation  and  escape  of  the  oxygene.  When  nitrous 
acid  has  been  made  to  assume  the  colours  before  men- 
tioned, if  the  glass  vessel  containing  it  be  hermetically 
sealed  and  kept  for  some  time  in  the  dark,  the  oxygene 
by  losing  its  light,  will  lose  its  elasticity;  and  being 
again  re- absorbed  by  the  nitrous  acid,  the  latter  will 
become  colourless,  as  before.  Mr.  Keir  mentions  an 
orange-coloured  nitrous  acid,  which,  by  long  keeping, 
became  green,  and  afterwards  of  a  deep  blue;  and  Berg- 
pian  says,  that  if,  to  a  concentrated  red  nitrous  acid, 
one-fourth  part  of  the  quantity  or  measure  of  water  be 


28  Philosophy  of  Permanent  Colours, 

added,  the  colour  will  be  changed  to  a  fine  green;  and 
to  a  blue,  by  the  addition  of  an  equal  measure  of  water; 
and  that  double  its  quantity  of  water  will  destroy  the 
colour.  Here  then  we  have  an  example  of  all  the  various 
colours  produced  by  the  two  species  of  air  which  almost 
exclusively  compose  our  atmosphere,  when  deprived  of 
their  elasticity,  and  mixed  in  particular  proportions  with 
more  or  less  dilution  by  water. 

In  the  same  manner,  colourless  nitric  acid,  when  ap- 
plied to  wool,  silk,  fur,  or  the  skins  of  animals,  their 
nails,  horns,  &c.,  renders  them  all  not  only  yellow,  but 
orange,  and  even  aurora-coloured.  M.  Berthollet  thinks, 
these  changes  are  produced  by  a  kind  of  combustion; 
but  I  am  persuaded  they  are  the  result  of  a  combination 
of  the  oxygene  with  the  nitrogene,  which  he  has  proved 
to  be  a  constituent  part  of  all  animal  substances;  these 
changes  being  exactly  similar  both  in  their  nature  and 
origin,  to  the  changes  of  colour  produced  as  before 
mentioned  in  the  nitrous  acid.  Were  these  colours  the 
effect  of  combustion,  why  are  they  not  likewise  pro- 
duced in  the  same  manner  upon  linens,  and  cottons, 
which  are  without  nitrogene,  but  contain  a  great  por- 
tion of  the  basis  of  charcoal,  and  ought  therefore  to  be 
more  liable  to  be  acted  upon  in  the  way  of  combustion, 
than  animal  substances? 

Long  before  the  properties  of  the  several  kinds  of  air 
were  known,  many  changes  of  colour  had  been  noticed 
as  produced  by  the  application  or  action  of  light;  and 
indeed  its  effects  are  so  remarkable,  in  many  cases,  that 
no  one  can  doubt  of  its  powerful  agency  in  these  and 
other  respects.*  The  principal  thing  to  be  ascertained 

*  Light  not  only  contributes  most  efficaciously  to  the  productiott 
of  some  colours  and  the  destruction  of  others,  but  it  greatly  weakens 
the  texture  and  fibres  of  sUk,  linen,  cotton,  &c.  when  they  are  long 


Philosophy  of  Permanent  Colours.  29 

on  this  point  is,  whether  the  colours  which  accompany, 
or  require  the  application  of  light,  result  in  each  parti- 
cular instance  directly  from  a  combination  of  it  with  the 
coloured  substance,  or  indirectly  from  its  particular  action 
in  occasioning  either  a  separation  of  oxy  gene,  or  a  com- 
bination thereof  with  the  coloured  matter?  M.  Senne- 
bier  attributes  the  effects  of  light  upon  colouring  mat- 
ters, to  a  direct  combination  of  the  former,  with  the 
latter;*  but  of  this,  though  it  may  be  true,  he  has  not 
alleged  any  sufficient  evidence,  so  far  as  I  am  capable 
of  judging;  and  there  are  many  facts  which  prove  that 
the  sun's  beams,  in  some  cases,  favour  the  action  of 
oxy  gene  upon,  and  its  combination  with,  colouring 
matters;  whilst  in  other  cases,  it  manifestly  produces 
opposite  effects  upon  these  matters,  by  decomposing  or 
separating  some  of  their  constituent  parts,  and  espe- 
cially the  oxygene  previously  united  to  them:  and  pro- 
bably these  are  the  only  ways  in  which  it  affects  colours; 
it  being  doubtful  whether  light  ever  unites  itself  so 
permanently  to  any  matter  as  it  must  do,  to  produce 
the  lasting  colours  given  by  dyeing. 

From  the  experiments  of  Beccari,  Meyer,  Schulz, 
Scheele,  and  Sennebier,  it  appears  that  muriate  of  silver 
(horned  silver),  which  is  nearly  of  a  pearl  white,  changes 
to  a  violet  colour,  and  from  thence  to  a  black,  in  the 
space  of  a  very  few  minutes,  when  exposed  to  the  sun's 
rays  in  a  transparent  glass;  and  this  change  Sennebier 
ascribes  solely  to  the  action  of  light;  since,  as  he  main- 
tains, the  muriate  of  silver  will  invariably  retain  its 
whiteness,  though  exposed  either  to  heat  or  cold,  and 
in  a  moist  or  a  dry  air,  or  in  vacuo,  if  secured  from  the 

exposed  to  the  direct  action  of  the  solar  rays;  as  may  be  seen  in 
window  curtains,  blinds,  &c.  which,  from  that  cause  only,  will,  in  a 
few  years,  tear  as  readily  as  brown  paper. 

*  See  "  Mem.  Physico-Chimiques  surTInfluencedela  Lumiere 
Solaire,"  &c.  torn.  ii.  and  iii. 


30  Philosophy  of  Permanent  Colours. 

accession  of  light,  and  of  what  he  calls  phlogistic  va- 
pours (probably  sulphuretted  hydrogenous  gas),  and 
that  it  loses  its  whiteness  only  by  the  application  of 
light,  and  then  only  in  proportion  to  its  quantity  or  in- 
tensity; so  that  when  the  sun's  rays  are  copiously  ap- 
plied by  a  lens,  the  muriate  of  silver  is  rendered  violet 
coloured  in  a  single  second.  By  covering  the  muriate 
of  silver  with  four  thicknesses  of  white  paper,  its  white- 
ness was  preserved;  one,  two,  and  three  thicknesses 
retarded,  but  did  not  prevent  its  finally  becoming  violet 
and  black.  Mr.  Sennebier  found  that  the  different  rays 
of  light,  under  the  same  circumstances,  coloured  the 
muriate  of  silver  with  different  degrees  of  celerity;  u  e. 
the  violet  rays  in  15  seconds,  the  purple  in  23  seconds, 
the  blue  in  29,  the  green  in  37,  the  yellow  in  5  minutes 
and  30  seconds,  the  orange  in  12  minutes^  and  the  red 
in  20;  but  the  rays  of  the  three  last  colours  would  not, 
as  he  relates,  produce  such  a  dark  violet  colour  in  any 
length  of  time,  as  w^as  thus  quickly  produced  by  the 
more  refrangible  rays.*  I  have^also  witnessed  some  of 
these,  and  other  changes  of  colour,  taking  place  in  mu- 
riated  or  horned  silver,  which  manifestly  result  from  an 
incipient  reduction  or  revival  of  the  metal,  and  with  it 
a  production  of  the  dark  colours  which  silver  always 
manifests  in  that  state;  and  in  confirmation  of  this,  I 
need  only  mention  what  I  have  several  times  observed, 
that  though  muriated  silver,  placed  at  the  bottom  of  a 
colourless  glass  vessel,  nearly  filled  with  water,  was 
made  violet  coloured  in  about  two  minutes,  by  the 
weak  light  of  a  room,  having  a  single  window  only,  and 

*  These  facts  which  formerly  appeared  unaccountable  and  ex- 
traordinary, may  now  be  readily  explained  by  those  which  Mr. 
Herschell  subsequently  discovered  and  published  (i.  e.  in  1800) 
respecting  the  composition  of  the  sun*s  beams,  and  the  very  difle- 
rent  powers  of  their  several  constituent  rays. 


Philosophy  of  Permanent  Colours,  31 

in  a  cloudy  day;  yet  a  direct  application  of  the  sun's  rays 
for  many  days  produced  no  change  of  colour,  when  the 
muriated  silver  was  covered  with  muriatic  acid  instead  of 
water;  a  revival  of  the  silver  not  taking  place,  whilst  so 
much  uncombined  muriatic  acid  remained  in  contact 
with  it. 

A  solution  of  silver  in  the  nitric  acid  likewise  changes 
colour  by  the  action  of  light,  and  becomes  black  thereby^ 
as  well  as  by  the  application  of  inflammable  substances, 
of  calcareous  earth,  and  every  thing  which  separates  a 
sufiicient  portion  of  the  oxygene.  It  also  gives  the  skin 
a  black  colour,  which  cannot  be  effaced,  but  by  a  re- 
moval or  change  of  the  skin  itself:  it  tinges  the  hair, 
nails,  and  other  animal  substances,  in  like  manner,  be- 
cause they  occasion  a  separation  of  so  much  of  the  oxy- 
gene as  is  necessary  for  that  purpose. 

Mercury  dissolved  in  nitric  acid,  being  washed  with 
water,  aflPords  a  yellow  oxide,  which,  when  exposed  to 
the  light  in  a  transparent  colourless  glass  vessel,  will 
become  black  on  the  side  to  which  the  light  is  applied, 
even  where  the  vessel  is  filled  with  water;  because  the 
light  extricates  a  part  of  the  oxygene;  this  yellow  oxide 
being  a  preparation  of  mercury,  with  but  a  very  small 
proportion  of  acid.  The  red  precipitate,  and  several 
other  preparations  of  mercury,  have  their  colours  changed 
even  under  water,  by  similar  means.  The  white  or  co- 
lourless solution  of  mercury,  by  the  nitric  acid,  when 
applied  to  animal  and  inflammable  substances,  tinges 
them  purple  and  black,  in  the  same  way,  and  from  the 
same  cause,  as  they  are  tinged  by  the  solution  of  silver. 
Similar  effects  happen  with  the  solution  and  oxide  of 
bismuth,  which  last  is  therefore  used  to  blacken  hair 
when  mixed  with  pomatum.  Almost  all  the  other  me- 
tals  afford  instances  of  changes  of  colour  more  or  less 
remarkable,  depending  both  upon  the  accession  and  the 
separation  of  oxygene;  and  in  many  of  these  light  has  a 


32  Philosophy  of  Permanent  Colours* 

considerable  influence  in  promoting  one  or  other  of  these 
effects. 

In  all  the  instances  lately  mentioned,  blackness  was 
produced  by  a  separation  of  vital  air  from  the  metallic 
basis;  but  there  are  others  in  which  it  results  from  the 
addition  or  accession  thereof.  Arsenic,  as  Mr.  Chaptal 
mentions,  when  first  sublimed,  is  of  a  shining  grey,  or 
steel  colour,  but  blackens  speedily  by  exposure  to  the 
air  ("  noircit  promptement  a  I'air;")  and  he  likewise  ob- 
serves, that  "  manganese,  precipitated  by  an  alkali  from 
its  solution,  was  found  to  be  a  whitish  gelatinous  sub- 
stance, which  soon  changed  colour,  and  became  blacky 
by  the  contact  of  air;  that,  having  been  a  witness  of 
this  phenomenon,  he  could  only  attribute  it  to  the  ab- 
sorption of  oxygenous  gas,  and  found  this  to  be  the 
case,  by  shaking  the  white  precipitate  in  glasses  filled 
with  that  gas,  by  which  the  black  colour  manifested 
itself  in  one  or  two  minutes,  and  a  considerable  part  of 
the  gas  was  found  to  have  been  absorbed."  Elemens 
de  Chimie,  tom.  ii.  p.  260. 

The  preceding  instances  relate  to  mineral  and  inor- 
ganical  substances;  there  are  many,  however,  which 
relate  to  the  colours  of  vegetable  and  animal  matters. 
Ray,  in  his  Historia  Plantarum,  printed  in  1686,  vol.  i. 
p.  15,  appears  to  have  discovered,  by  several  experi- 
ments and  observations,  that  the  green  colour  of  plants 
depended  chiefly  upon  the  influence  of  light:  he  had 
found  that  they  were  green,  whilst  vegetating  under  a 
transparent  glass  bell  exposed  to  the  light,  and  that 
when  growing  in  obscurity  under  an  opaque  vessel,  they 
lost  their  green,  and  acquired  a  pale  whitish  yellow; 
their  stalks,  at  the  same  time,  becoming  long,  slender, 
and  feeble,  and  their  leaves  small.  And  these  effects  he 
ascribed  to  the  want  of  light,  rather  than  of  either  air  or 
heat:  "  Nobis  tamen  non  tarn  aer  quam  lumen,  luminisve 


Philosophy  of  Permanent  Colours,  55 

actio  colons  in  plantarum  foliis  viridis  caussa  esse  vi- 
detur." — "  Ad  hunc  aiitem  colorem  inducendum  non 
fequiritur  calor,"  &c.  Mr.  Bonnet  has  since  confirmed 
Ray's  conclusions  upon  this  subject,  and  added  several 
curious  facts,  resulting  from  a  variety  of  experiments 
related  in  the  fourth  and  fifth  volumes  of  his  works:  but 
it  is  Mr.  Sennebier  who  has  done  most,  and  carried  his 
inquiries  farthest  respecting  it,  as  appears  by  his  "  Me- 
moires  Physico-Chimiques  sur  I'lnfluence  de  la  Lu- 
miere  Solaire,"  &c.  in  3  vols.  8vo. 

It  is  now  well  ascertained,  that  vegetables,  growing 
in  the  light,  give  out  oxygene  gas,  (pure  vital  air;)  and 
Dr.  Ingenhouz,  by  a  great  number  of  experiments,  has 
proved,  or  conceives  himself  to  have  proved,  that  in  the 
dark  they  give  out  the  carbonic  acid  gas  (fixed  air;) 
though  this  has  been  doubted  by  others,  and  particu- 
larly by  Mr.  Sennebier,  who  conceives,  that,  in  these 
cases,  it  was  the  pure  air  vitiated  by  some  disease  or 
decomposition  of  the  plant  itself:  Dr.  Ingenhouz,  how- 
ever, in  his  last  publication,  adheres  to  his  former  opi- 
nion, and  supports  it  with  new  facts  and  arguments.  Be 
this,  however,  right  or  wrong,  there  is  no  room  to  doubt 
but  that  healthy  plants,  growing  in  the  solar  light,  de- 
compose both  water  and  carbonic  acid  gas;  and,  appro- 
priating to  themselves  the  hydrogene,  or  inflammable 
air  (which  is  a  constituent  part  of  water),  and  the  car- 
bonaceous matter,  or  basis  of  the  carbonic  acid,  with 
perhaps  a  small  portion  of  the  oxygene,  they  emit  the 
rest  in  the  form  of  vital  air,  which  the  light  seems  t6 
separate,  by  combining  with  and  rendering  it  elastic,  in 
the  same  manner  as  it  separates  the  oxygene  from  th^ 
calces  or  oxides  of  metals,  Sec.  But  when  plants  vege* 
tate  in  obscurity,  no  such  separation  can  take  place: 
indeed,  the  water  imbibed  by  the  plants  seems  not  to 
be  properly  decomposed,  unless  their  living  powers  be 

Vol.  I.  E 


34  Philosophy  of  Permanent  Colours, 

aided  by  the  stimulus  of  light,  and  by  its  affinity  for 
the  oxygene.  There  is,  therefore,  an  accumulation  of 
this  latter  substance,  and  a  want  of  inflammable  air  to 
compose  the  resinous  matter,  by  which  the  green  co- 
lour of  the  plant  is  produced;  and  this  colouring  matter 
being  very  sparingly  formed,  and  at  the  same  time  com- 
bined with  an  excess  of  oxygene,  the  plant,  instead  of 
its  natural  greenness,  exhibits  only  a  white  or  pale  straw 
colour.  Mr.  Sennebier  found  that  plants,  in  this  state, 
received  a  deeper  green,  and  in  less  time,  by  exposure 
to  the  violet  rays  of  light,  than  to  those  which  were  less 
refrangible,  as  was  the  case  in  colouring  the  muriate  of 
silver.  He  also  found  that  plants  left  to  vegetate  without 
light,  under  vessels  filled  either  with  nitrogene,  or  hy- 
drogene,  did  not  lose  their  green  colour,  as  when  sur- 
rounded  by  common  atmospheric  air.  In  carbonic  acid 
gas  they  soon  perished.  Dr.  Ingenhouz  also  observed, 
that  on  mixing  a  little  hy drogene  with  either  the  com- 
mon or  the  vital  air  in  which  a  plant  was  growing,  un- 
der a  transparent  glass,  the  green  colour  of  the  plant 
soon  became  deeper.  In  these  cases  there  seems  to 
have  been  an  absorption  of  the  hydrogene,  affording  an 
increase  of  the  resinous  colouring  matter. 

Mr.  Sennebier  also  found,  that  the  red  tinctures  of 
orcanette,^  safflower,  kermes,  gum  lac,  and  cochineal, 
were  made  yellow  by  exposure  to  the  sun's  rays;  and 
the  tincture  of  dragon's  blood  was  thereby  deprived  of 
all  colour:  in  these  cases  the  alcohol^  or  spirits  of  wine, 
assisted  the  action  of  the  sun's  rays  in  decomposing  the 
several  colouring  matters,  probably  by  abstracting  and 
combining;  with  their  oxygene;  because  it  was  found 
that  the  aqueous  infusions  of  orcanette,  kermes,  and  co- 
chineal, suffered  no  change  by  the  like  exposure;  though 

*  AiKhusa  Hnctoria*  Lin. 


Philosophy  of  Permanent  Colours.  .^5 

indeed  the  infusions  of  safflovver,  dragon's  blood,  and 
gum  lac,  were  changed  by  it;  perhaps  because  they  con- 
tain a  resinous  matter  which  might  have  co-operated 
with  the  rays  of  light,  in  the  same  way  as  the  spirit  of 
wine  is  supposed  to  have  done.  Mr.  Sennebier  observed, 
that  the  petals  of  damask  roses  afforded  a  kind  of  brick 
colour  to  spirits  of  wine,  when  put  into  it;  and  that  this, 
bs'  a  few  minutes  exposure  to  the  common  light,  be- 
came of  a  fine  violet  colour;  which,  however,  was  soon 
destroyed,  by  a  direct  application  of  the  sun's  light, 
imless  when  a  few  drops  of  some  of  the  strong  acids 
were  added;  in  which  case,  the  colour  withstood  the 
sun's  rays  for  several  months.  From  these  instances  I 
conclude,  that  the  colour  of  roses  depends  on  a  certain 
proportion  of  oxygene;  that  the  light,  aided  by  the  affi- 
nity of  the  spirits  of  wine  for  oxygene,  produces  a  sepa- 
ration of  it,  and  destroys  the  colour;  but  that  these 
effects  are  obviated,  as  might  be  expected,  by  the  ad- 
dition of  acids  containing  and  affording  a  supply  of 
oxygene.  And  that  this  was  the  fact,  seems  evident 
from  this  observation,  made  by  Mr.  Sennebier,  that 
when  the  petals  of  the  roses  had  been  rendered  white, 
by  imparting  their  colour  to  the  spirit  of  wine,  they 
regained  it  on  being  taken  out,  and  exposed  to  the  air, 
even  in  a  dark  place;  though  they  did  it  much  quicker 
in  the  light;  but  not  at  all  in  a  vessel  containing  only 
nitrogene  surrounded  by  quicksilver,  even  when  aided 
by  an  immediate  application  of  the  sun's  light;  which 
clearly  proves,  that  the  restitution  of  oxygene  was  in- 
dispensably necessary  to  the  restitution  of  their  colour. 
In  the  same  way  sulphureous  acid  whitens  roses,  by  de- 
priving them  of  their  oxygene;  and  the  sulphuric  acid 
revives  the  colour,  by  restoring  it.*  Mr.  Sennebier  also 

*  The  sulphureous  or  volatile  vitriolic  acid,  not  being  saturated 
with  oxygene,  is  disposed  to  attract  it  from  other  matters  in  con- 


36  Philosophy  of  Permanent  Colours. 

found  that  the  red  skins  of  peaches  became  white  in 
spirits  of  wine,  like  the  petals  of  roses,  and,  like  them, 
regained  their  colour  by  exposure  to  the  air;  as  did  also 
the  red  skins  of  plumbs.  He  likewise  observed,  that  the 
water-colours  used  by  painters,  if  covered  by  a  solution 
of  fish  glue  or  isinglass,  and  then  varnished,  withstood 
the  action  of  the  sun's  rays  much  longer  than  if  var- 
nished without  the  fish-glue;  which  last  seems  to  have 
prevented  the  varnish  from  co-operating  with  the  light 
in  extricating  the  oxygene  of  the  colouring  matters,  as, 
from  its  inflammable  nature,  it  would  do,  if  in  imme- 
diate contact  with  them.  Negro  children  when  first  born 
are  white,  as  plants  are  when  they  first  shoot  above  the 
earth,  though  they  become  black  in  a  few  days,  after 
being  exposed  to  the  light,  as  plants  become  green,  and 
probably  from  the  same  cause. 

In  like  manner  the  hair  of  such  kittens,  puppies,  &c. 
as  are  intended  by  nature  to  become  decidedly  black, 
is  immediately  after  birth  only  of  a  brownish  black;  but 
it  gradually  darkens  externally.  Though  the  hair  of  the 
blackest  cats  and  dogs  will  be  found,  even  in  old  age, 
not  to  be  black  at  the  roots  near  the  skin^  where  it  is 
most  secluded  from  the  light. 

Mr.  Sennebier  mentions,  upon  the  authority  of  Scheele, 
that  the  Nereis  lacustris,  is  red  whilst  living  in  places 
accessible  to  the  sun's  rays,  and  white  when  living  in 
obscurity;  and  M.  Dorthes  asserts,  (Ann.  de  Chimie, 
tom.  ii.)  that  most  of  the  larva  of  insects,  inhabiting 
the  dark  cavities  of  animals,  trees,  fruit,  &.c.  are  white; 
and  that  having  forced  a  variety  of  them  to  live  under 
transparent  glasses,  exposed  to  the  light,  they  gradually 
became  brown.  But  the  most  decisive  and  interesting 

tact  with  it;  and  by  so  doing,  it  not  only  whitens  roses,  but  silk, 
wool,  and  other  substances,  rcDdercd  yellow  by  being  united  to  a 
certain  portion  of  oxygene. 


Philosophy  of  Permanent  Colours,  37 

proof  of  the  action  of  light,  m  producing  various  colours 
by  promoting  a  separation  of  oxygene  from  animal  co- 
louring matter,  will  be  found  by  the  effects  which  I  shall 
notice  hereafter,  when  treating  of  the  celebrated  purple 
of  the  ancients. 

The  preceding  are  examples  of  animal  and  vegetable 
colours  produced,  changed,  or  destroyed,  either  by  the 
action,  or  the  want  of  light,  exerted  in  separating  their 
oxygene.  In  many  other  cases,  however,  the  affinity  of 
light  is  very  differently  exerted,  upon  colouring  matters, 
by  promoting  a  combination  of  oxygene  with  them. 

The  green  colour  of  the  leaves  of  plants  resides  in  a 
resinous  substance,  which  being  dissolved  and  extract- 
ed by  spirit  of  wine,  produces  a  green  tincture;  and  Mr^ 
Sennebier  having  exposed  this  to  the  rays  of  the  sun, 
in  a  clear  transparent  glass,  but  half  filled,  he  found, 
upon  repeated  trials,  that  the  colour  was  generally  des- 
troyed in  about  twenty  minutes,  and  a  yellowish  sub- 
stance was  precipitated  to  the  bottom;  which  seems  to 
have  been  the  colouring  matter  saturated  with  oxygene: 
but  when  the  glass  was  completely  filled  with  the  green 
tincture,  and  closely  stopped,  he  found,  that  the  strongest 
action  of  the  sun's  rays  upon  it,  during  four  months, 
did  not  weaken  in  any  degree,  the  green  colour,  because 
all  oxygene  was  excluded,  and  the  rays  of  light,  with- 
out it,  were  unable  to  effect  any  change.  When  nitro- 
gene  was  inclosed  in  a  vessel  partly  filled  with  this  green 
tincture,  the  latter  suffered  little  or  no  change,  by  long 
exposure  to  the  direct  action  of  the  sun's  light;  but  if, 
instead  of  this,  he  substituted  pure  vital  air,  the  green 
colour  was  most  rapidly  destroyed.  Mr.  Sennebier  also 
found,  that  the  dark  red  juice  of  black  cherries  very 
soon  lost  its  colour,  when  exposed  to  the  sun's  raj^s, 
but  that  a  tincture  of  those  cherries  in  spirit  of  wine, 
preserved  its  colour  in  the  same  circumstances;   the 


•38  Philosophy  of  Permanent  Colours, 

spirit  of  wine,  as  I  conceive,  affording  a  covering  and 
defence  to  the  colouring  matter  of  the  cherries,  against 
the  action  and  farther  combination  of  oxygene  or  vital 
air.  Here  the  effect  was  directly  opposite  to  that  with 
roses,  lately  mentioned.  M.  Fabroni  has  also  asserted, 
(Ann.  de  Chimie,  tom.  xxv.)  that  the  fresh  juice  of  the 
aloe  succotrina  angusti  folia,  by  mere  exposure  to  the 
atmosphere,  either  with  or  without  the  contact  of  light, 
soon  became  red;  first,  at  the  parts  most  accessible  to 
the  air,  and  afterwards  in  other  parts,  and  that  it  finally 
became  of  a  very  dark,  but  very  lively  purple:  and  he 
convinced  himself  that  this  change  resulted  exclusively 
from  an  absorption  and  combination  of  oxygene.  There 
are  many  other  instances  of  changes  of  colour  by  an  ab- 
sorption of  oxygene,  with  or  without  the  assistance  of 
light;  and  in  particular  two  experiments  made  by  M. 
Bcrthollet.  In  the  first,  he  "  inverted,  over  mercury,  a 
bottle  half  full  of  the  green  solution  (employed  by  Mr. 
Sennebier,)  and  exposed  it  to  the  light  of  the  sun;  and 
when  the  colour  was  discharged,  the  mercury  was  found 
to  have  risen  in  the  bottle^  and  consequently  vital  air 
must  have  been  absorbed;  the  oxygene  having  united 
with  the  colouring  matter."  In  the  second  experiment, 
he  "  placed  a  tincture  of  turnsol,  in  contact  with  vital 
air,  over  mercury,  in  the  dark,  and  he  also  exposed  a 
similar  tincture  to  the  light  of  the  sun;  the  former  con- 
tinued unchanged  for  a  considerable  length  of  time,  and 
the  vital  air  had  suffered  no  diminution;  but  the  latter 
had  lost  much  of  its  colour,  was  become  red,  and  the 
air  was  in  a  great  measure  absorbed,"  &c. 

M.  Fourcroy  has  also  demonstrated,  (see  Ann.  de 
Chimie,  tom.  v.)  that  a  variety  of  colouring  matters, 
extracted  by  water,  and  left  exposed  to  the  air,  combin- 
ed with  its  oxygene,  and  thereby  not  only  assumed  nevi^" 
colours,  but  became  much  more  fixed  and  permanent; 


Philosophy  of  Permanent  Colours.  39 

which  happens  likewise  in  the  production  of  indigo,  as 
will  be  proved  hereafter. 

1  have  now  noticed  the  principal  facts  respecting  the 
powerful  agencies  of  solar  light,  in  producing,  changing, 
and  destroying  mineral,  vegetable,  and  animal  colours; 
which  agencies  as  far  as  we  know,  or  can  judge,  seem 
to  be  principally,  if  not  exclusively,  exerted,  in  promot- 
ing, under  particular  circumstances,  and  with  particular 
coloured,  or  colouring,  matters,  cw  abstraction  or  diminu- 
tion of  their  oxygene;  and  with  other  matters  and  other 
circumstances,  in  causing  a  new  or  additional  combina- 
tion of  it. 

These  opposite  effects,  may  be  now  explained  in  con- 
sequence of  recent  discoveries  respecting  the  sun's 
beams.  Newton  taught  us,  that  when  the  rays  of  which 
they  consist  are  transmitted  through  a  triangular  prism, 
and  received  upon  white  paper,  those  most  distinctly 
perceptible^  are  the  red,  orange,  yellow,  green,  blue,  in- 
digo, and  violet;  and  that  if  the  coloured  image  or  spect- 
rum be  divided  into  360  parts,  the  red  will  occupy  45 
of  these  parts,  the  orange  27,  the  yellow  48,  the  green 
60,  the  blue  60,  the  indigo  40,  and  the  violet  80;  and 
that  the  red  are  refracted  the  least;  the  violet  the  most; 
and  the  other  rays  inversely  in  the  order  in  which  they 
have  been  arranged,  and  he  supposed  them  to  vary  in 
the  size  of  their  particles,  according  to  this  order;  those 
of  the  violet  being  the  smallest.  It  has,  however,  been 
recently  ascertained  by  Dr,  Herschell,  (see  Philosoph. 
Transactions  for  1800,  p.  267.)  and  by  the  experiments 
of  Sir  H.  Englefield  and  others,  that  the  solar  beams 
comprehend  three  sorts  of  rays;  viz.  one  which  excite 
heat  and  promote  oxidation,  or  the  combination  of  oxy- 
gene with  different  matters;  another  which  illuminate; 
and  a  third  which  c/eoxidize,  or  cause  the  separation  of 
oxygene.  He  found  the  yellow,  and  the  pale  green  rays, 


40  Philosophy  of  Permanent  Colour s* 

to  possess  the  greatest  power  of  illuminating,  and  iht 
violet  the  least;  and  the  red  rays  to  possess  the  greatest 
power  of  heating,  and  the  violet  the  least.  But  beyond 
the  red  rays,  there  are  certain  invisible  heating  rays, 
which  raise  the  thermometer  higher  than  even  the  red 
rays.  Moreover,  at  the  other  extremity,  a  little  beyond 
the  violet  rays,  not  only  the  thermometer  is  not  affected, 
but  there  are  there,  certain  other  invisible  rays,  wliich 
produce,  very  efficaciously,  particular  chemical  effects; 
one  of  which  is  that  of  changing  from  white  to  blacky 
the  colour  of  a  precipitate  of  the  muriate  of  the  silver  just 
made.  This  is,  indeed,  done  most  rapidly,  by  the  col- 
lected rays  of  the  sun's  beams,  but  the  separate  rays  do 
it  with  greater  energy,  in  proportion  as  they  are  nearest 
to  the  invisible  rays,  at  the  violet  extremity.  Sir  H. 
Davy  also  states,  that  "if  moist  horned  silver,  (muriate 
of  silver)  be  exposed  to  the  different  rays  of  the  prisma- 
tic spectrum,  it  will  be  found  that  no  effect  is  produced 
upon  it  by  the  least  refrangible  rays,  which  occasion  the 
greatest  heat,  without  light;  a  slight  discolouration  only, 
will  be  occasioned  by  the  red  rays;  the  effect  of  black- 
ening, will  be  greatest  towards  the  violet  part  of  the 
spectrum;  and  in  a  space  beyond  the  violet,  where  there 
is  no  sensible  heat  or  light,  the  chemical  effect  will  be 
very  distinct."  "  This  observation,  (he  adds)  made  by 
M.  Ritter  and  Dr.  Wollaston,  proves  that  there  are  rays 
more  refrangible  than  the  rays  producing  light  and  heat; 
and  from  the  observations  of  M.  Berthollet,  it  appears 
that  muriatic  acid  gas  is  formed,  when  horn  silver  is 
blackened  by  light,  so  that  they  may  be  called  hydroge- 
nating  rays,"  p.  211.  Sir  H.  Davy  farther  observes,  in 
the  next  page,  that  he  "  found  that  the  puce  (or  Flea) 
coloured  oxide  of  lead  when  moistened,  gradually  gain- 
ed a  tint  of  red  in  the  least  refrangible  rays,  and  at  last 
became  black,  but  was  iiot  affected  in  the  most  refran- 


Philosophy  of  Permanent  Colours.  4i 

gible  rays;  and  the  same  change  was  produced,  by  ex- 
posing it  to  a  current  of  hydrogene  gas.  The  oxide  of 
mercury  procured  by  a  solution  of  potassa  and  calomel, 
exposed  to  the  spectrum,  was  not  changed  in  the  most 
refrangible  rays,  but  became  red  in  the  least  refrangible 
rays,  which  must  have  depended  upon  its  absorbing 
oxygene." 

Dr.  Wollaston  found  that  the  substance  called  gum- 
guaiacum,  when  exposed  in  the  most  refrangible  rays, 
beyond  the  violet  extremity,  was  changed  from  its 
yellowish  colour  to  green;  and  that  it  was  again  made 
yellow,  by  the  least  refrangible  rays.  One  of  which  ef- 
fects must  have  resulted  from  a  separation,  and  the  other 
from  an  absorption  of  oxygene. 

The  oxygenating  power  of  the  solar  rays  is,  however, 
that  which  M.  Berthollet  seems  exclusively,  and  as  I 
think  erroneously,  to  insist  upon,  as  occasioning,  either 
with  or  without  the  aid  of  light,  all  the  changes  and  in- 
juries to  which  animal  and  vegetable  colouring  matters 
are  liable;  and  he  deems  the  action  and  effects  of  oxy- 
gene in  these  cases  to  be  similar  to  those  of  combustion.* 
*'In  considering  the  effects  of  air  on  colours  (says  he,) 
it  is  necessary  to  make  a  distinction  between  those  pro- 
duced by  metallic  oxides,  and  those  produced  by  the 
colouring  particles,"  meaning  those  of  an  animal  or  a 
vegetable  nature;  the  modifications  of  the  former  are, 
says  he,  "  entirely  owing  to  different  proportions  of 
oxygene;"  but  I  have  been  led  by  observation,  he  adds, 
"  to  form  a  different  opinion  of  the  latter;"  meaning 
those  with  which  the  oxy-muriatic  acid  had  exhibited 

*  "  Get  effet  doit  etre  considere  comme  une  veritable  combustion. 
Par  la,  le  charbon  qui  entre  dans  la  composition  des  parties  colo- 
rantes,  devient  predominant,  et  la  couleur  passe  ordinairement 
au  jaune,  au  fauve,  au  brun;  ou  cette  degradation  en  s'alliant  avec 
ce  qui  reste  de  la  premiere  couleur,  produit  d'autres  apparences." 

Vol.  I.  F 


42  Philosophy  of  Permanent  Colours. 

different  phenomena,  sometimes  discharging  their  colour, 
and  producing  whiteness,  but  most  frequently  rendering 
them  yellow,  fawn,  or  root-coloured,  or  brown  or  black, 
according  to  the  intensity  of  its  action:  and  he  remarks, 
that  he  had  found,  by  comparison,  that  when  the  colour- 
ing particles  were  rendered  yellow,  fawn-coloured,  or 
brown,  by  the  oxy-muriatic  acid,  effects  were  produced 
similar  to  those  of  combustion;  and  that  they  were 
"  owing  to  the  destruction  of  the  hydrogene;  which,  as 
it  combines  with  oxygenc  more  easily,  and  at  a  lower 
temperature  than  charcoal  does,  leaves  the  latter  predo- 
minant; so  that  the  natural  colour  of  charcoal  is  more  or 
less  blended  with  that  which  before  existed;"*  and  as 

*  Messrs.  Lavoisier,  Berthollet,  and  other  pneumatic  chemists, 
have  considered  the  black  colour  of  charcoal  as  naturally  existing^ 
in  the  vegetable  matter  from  which  it  is  formed,  and  not  as  the 
result  or  effect  of  combustion.  To  me,  however,  charcoal  seems  to 
be  a  kind  of  vegetable  oxide^  consisting  of  the  carbonaceous  basis, 
united  to  a  certain  portion  of  oxygene,  enough  to  render  this  basis 
black  (as  it  occasions  the  blackness  of  manganese,)  but  not  enough 
to  saturate  and  convert  it  into  carbonic  acid  gas.  Hard  woods  con- 
tain so  great  a  portion  of  the  basis  of  charcoal,  that  if  it  really  exist- 
ed therein,  with  its  black  colour,  previous  to  combustion,  it  is  im- 
possible to  conceive  how  they  should  ever  appear  v.-hite,  yellovfj 
red,  Sec,  since  in  dyeing,  &c.  we  find,  that  laying  other  colours  upon 
a  black  ground,  increases  the  blackness.  Neither  do  1  think  that 
this  blackness  is  the  only  circumstance  in  which  charcoal  differs 
from  its  basis,  or  the  state  in  which  the  vegetable  part  thereof  ex- 
isted previous  to  combustion:  on  the  contrary,  its  oxidation,  or  com- 
bination with  oxygene,  manifestly  gives  it  new  and  very  remarka- 
ble properties.  This  basis,  is,  indeed,  never  converted  into  charcoal, 
but  by  such  a  degree  of  heat,  and  in  such  circumstances,  as  must 
necessarily  occasion  its  combination  with  oxygene;  and  when  this 
conversion  is  made,  the  charcoal  is  rendered  infinitely  more  indes- 
tructible than  any  other  vegetable  matter,  as  it  will  resist  the  com- 
bined action  of  sun,  air,  moisture,  &c.  for  hundreds  of  years;  and 
indeed  it  can  hardly  be  destroyed,  but  by  such  farther  combustion 
and  combination  with  oxygene,  as  will  change  it  into  carbonic  acid 


Philosophy  of  Permanent  Colours,  43 

^*  the  light  of  the  sun  considerably  accelerates  the  de- 
struction of  colours,"  he  concludes  that  it  ought,  if  his 

gas.  This  indestructibility,  or  stability,  as  well  as  the  black  colour, 
of  charcoal,  therefore  manifestly  result  from  the  combination  of 
oxygene  with  its  basis.  Did  it  really  exist,  nvith  its  black  colour  natu- 
rally  in  wood  and  other  vegetables,  why  do  we  not  find  it  remain- 
ing intire  after  the  other  parts  of  vegetables  are  separated  or  de- 
stroyed by  fermentation,  ^putrefaction,  &c.;  And  why  docs  it  decay 
and  rot  with  them  undistviguished,  contrary  to  what  happens  when 
it  occurs  separately,  in  the  form  of  clmrcoal?  And  why,  when  it  has 
assumed  this  form,  will  it  not  recombine  with  matters  similar  to 
those  which  were  separated  from  it,  and  enter  with  them  into  fer- 
mentation, Sec.  as  it  surely  ought  to  do,  if  it  had  acquired  no  new 
property,  and  only  been  left  in  a  distinct  form,  by  the  simple  ab- 
straction of  those  matters. 

The  preceding  observations  respecting  charcoal,  were  first  print- 
ed in  the  year  1793.  It  did  not  then  accord  with  my  purpose,  to 
enter  upon  a  minute  examination  of  the  several  constituent  parts 
of  charcoal;  I  wished  only  to  convince  my  readers  that  it  was  not  a 
simple  substance,  naturally  formed,  and  existing  with  its  black  co- 
lour in  vegetable  matter;  and  that  when  dyed  colours  faded,  and 
became  brown  or  dark  coloured,  by  exposure  to  the  sun  and  air, 
this  change  did  not  happen,  as  M.  Berthollet  had  conceived,  because 
the  supposed  naturally  black  colour  of  the  charcoal,  contained  in  the 
I'egetable  dyes,  was  rendered  visible,  and  firedominant,  by  a  separa- 
tion of  the  other  matters,  which  had  been  in  union  with  it,  ("  de 
sorte  que  la  couleur  firofire  au  charbon,  se  mele  plus  ou  moins,  a 
celle  qui  preexistait."  Berthollet,  torn.  i.  p.  133).  To  produce  this 
conviction,  I  thought  it  only  necessary  that  my  readers  should, 
without  bias,  exercise  their  senses  and  understandings.  Since  that 
time,  the  nature  and  composition  of  charcoal  have  been  nearly  as- 
certained; but  I  think  I  may  claim  the  merit  of  having  first  occasi- 
oned a  distrust  «f  the  doctrine  of  M.  Lavoisier  on  this  subject,  and 
thereby  promoted  the  subsequent  experiments  and  inquiries. 

Dr.  Thompson,  one  of  our  best  systematic  chemical  writers, 
makes  the  following  observation  in  the  first  volume  of  his  system 
of  chemistry,  viz.  "Lavoisier  supposed  pure  charcoal  xohesi  simflle 
substance,  and  for  that  reason  invented  the  term  carbon  to  distin- 
guish it.  But  other  philosophers  were  of  opinion  that  charcoal  is  a 
compound  body,  and  that  it  is  composed  of  carbon  and  oxygene. 
The  truth  of  this  opinion,  whichy  as  far  as  I  know^  ivas  first  main' 


44  Philosophy  of  Permanent  Colours. 

theory  be  well  founded,  "  to  favour  the  combination  of 
oxygene,  and  the  combustion  thereby  produced."* 

In  thus  ascribing  the  decays  of  vegetable  and  animal 
colouring  matters  generally^  to  effects  or  changes  similar 
to  those  of  combustion,  M.  Berthollet  has,  I  think,  gone 
farther  than  is  warrantable  by  facts.  It  cannot,  I  am 
persuaded,  be  his  intention  that  we  should  apply  the 
term  of  combustion  to  alterations  which  result  from  a 
simple  addition  of  oxygene  to  colouring  matters,  with- 
out any  destruction  or  decomposition  of  their  constituent 
parts;  though  a  great  many  of  the  alterations  and  extinc- 
tions of  these  colours  evidently  arise  only  from  such 
simple  additions.  The  nitric,  sulphuric,  and  other  acids 
containing  oxygene,  have  the  power  not  only  of  weak- 
ening, but  of  rendering  latent  for  a  time,  the  colours  of 
many  tingent  matters;  not  however  by  any  effect  which 
can  properly  be  denominated  a  combustion,  but  rather 
by  a  change  in  their  several  affinities  or  attractions,  for 
particular  rays  of  light  in  preference  to  other  rays;  but 
none  of  their  parts  being  destroyed,  or  carried  away,  the 
addition  of  an  alkali,  or  of  a  calcareous  carbonate^  will 
generally  undo  such  alteration,  and  restore  the  original 
colour,  by  decomposing  and  neutralizing  the  acid  or 
oxygene  which  had  caused  the  alteration.  Of  this  nume- 
rous instances  might  be  given;  it  will  however  be  suf- 
ficient to  mention,  what  most  people  have  seen,  that 
ink,  dropped  into  a  glass  of  diluted  nitric,  or  vitriolic 
acid,  will  lose  its  colour,  and  that  it  may  be  again  re- 
stored by  adding  a  suitable  portion  of  vegetable  or  fossil 
alkali;  and  that  this  may  be  done  several  times  with  the 

tained  by  Dr,  Bancroft,  has  been  lately  established  by  the  experi- 
ments of  M.  Giiyton  Morveau.'*  To  these  have  been  more  recently 
added,  the  accurate  researches  of  Messrs.  Allen  and  Pepys. 
*  Elements  o^the  Art  of  Dyeing,  chap.  ill. 


Philosophy  of  Permanent  Colours.  45 

same  ink,  and  therefore  the  change,  or  loss  of  colour, 
could  not  have  been  the  effect  of  combustion.  The  pro. 
duction  and  existence  of  each  particular  colour,  depends 
upon  precise,  and  often  very  minute  proportions  of  the 
constituent  parts  of  the  colouring  matter,  and  it  may, 
therefore,  be  changed,  and  in  many  cases  even  destroy- 
ed, by  every  thing  capable  o^  altering  these  precise  pro- 
portions;  and  as  this  may  be  done  by  very  opposite 
causes,  we  are  not  warranted  in  ascribing  the  decays  oi 
colours  generally  to  combustion  only,  or  indeed  to  any 
one  cause  exclusively.  Many  colours  are  as  much  in- 
jured by  muriatic  acid,  as  by  the  sulphuric  or  nitric: 
and  as  the  former  is  now  generally  admitted  to  contain 
no  oxygene,  or  to  contain  it  so  inseparably  combined^  that 
no  combustion  can  take  place  by  means  thereof,  we 
must  necessarily  infer,  that  the  effects  of  the  muriatic 
acid,  are  not  occasioned  by  combustion,  which  muriatic 
acid  does  not  produce. 

Mr.  Sennebier  exposed  a  great  variety  of  woods  to 
the  action  of  the  sun  and  air,  and  found  all  their  colours 
very  soon  affected.  The  white  woods  were  generally 
made  brown,  and  the  red  and  violet  changed  either  to 
yellow  or  black.  Guaiacum  was  rendered  green;  the  oak 
and  the  cedar  were  whitened^  as  were  the  brown  woods 
generally;  several  of  these  effects,  and  especially  the 
whitening,  do  not  resemble  those  of  combustion,  any 
more  than  the  bleaching  of  wax  and  tallow^  by  exposure 
to  atmospheric  air. 

The  colour  of  each  particular  substance  results  from  its 
peculiar  constitution,  producing  in  it  a  particular  affinity 
or  attraction  for  certain  rays  of  light,  and  a  disposition 
to  reflect  or  transmit  certain  other  rays;  and  in  this  re- 
spect it  may  doubtless  suffer  very  considerable  changes, 
without  any  effects  similar  to  those  of  combustion.  And 
indeed  the  changes  of  colour  which  arise  from  the  ac 


46  Philosophy  of  Permanent  Colours. 

cess  of  vital  or  atmospheric  air,  seldom  resemble  those 
which  the  mere  predomineiice  of  blackness  (the  supposed 
natural  colour  of  charcoal)  would  produce;  though  this 
may  have  been  the  case  with  the  colouring  matter  of 
brown  or  unbleached  linen,  upon  which  M.  Berthollet's 
experiments  were  principally  made. 

But  whether  the  action  of  vital  air,  or  its  basis,  in 
promoting  the  decays  of  a  few  particular  colours,  ought 
to  be  denominated  a  combustion  or  not,  I  am  confident 
that,  at  least,  some  others  are  liable  to  be  impaired,  not 
so  much  by  an  accession  of  oxygene^  as  by  the  loss  of  it; 
an  effect,  of  which  I  have  already  enumerated  several 
examples,  among  animal  and  vegetable,  as  well  as 
mineral  substances,  deriving  their  colours  from  a  com- 
bination with  certain  portions  of  oxygene;  and  of  these 
I  might  easily  augment  the  number. 

Hook  and  Lower  long  since  noticed  the  difference  of 
colour  in  arterial  and  venal  blood;  and  it  has  been  since 
proved,  by  numerous  experiments,  that  the  fine  vermi- 
lion colour  of  the  former,  is  produced  solely  by  vital 
air,  which  it  is  capable  of  acquiring  even  through  blad- 
ders, the  coats  of  blood-vessels,  &c.  And  very  recently, 
Mr.  Hassenfratz  seems  to  have  proved  (see  Ann.  de 
Chimie,  tom.  ix.),  that  as  this  fine  red  colour  is  gained 
by  a  dissolution  of  oxygene  in  the  arterial  blood,  so  it 
is  lost,  and  the  dark  colour  of  the  venal  blood  restored, 
by  a  separation  of  the  oxygt  ne. 

That  the  blue  colour  of  indigo  absolutely  depends 
upon  a  certain  portion  of  oxygene,  has  been  already 
mentioned,  and  I  shall  hereafter  give  some  curious  il- 
lustrations of  this  fact,  from  which  it  will  appear  that  a 
solution  of  indigo,  by  losing  its  oxygene,  may  be  ren- 
dered as  pellucid,  and,  excepting  a  very  slight  straw- 
coloured  linge,  as  colourless  as  water,  and  that  it  will 
afterwards  speedily  return,  through  all  the  shades  of 


Philosophy  of  Permanent  Colours.  47 

yellow  and  green,  lo  its  original  deep  blue,  only  by  ex- 
posure to  atmospheric  or  vital  air.  Similar  to  this  is  the 
fact  long  since  observed  by  the  Abbe  Nollet,  of  the 
tincture  of  archil  (orchella)  employed  to  colour  the  spirit 
of  wine  used  in  thermometers,  which  after  some  time 
loses  its  purple  colour,  but  soon  recovers  it  again  upon 
being  exposed  to  atmospheric  air.  And  this  also  happens 
to  the  infusion  of  turnsol,  and  to  syrup  of  violets,  which 
both  lose  their  colours  when  secluded  from  air,  and  re- 
gain them  when  placed  in  contact  with  it.*  Many  other 
examples  of  the  like  effects  might  be  mentioned  here; 
but  to  avoid  repetitions,  I  beg  leave  to  refer  my  readers 
to  subsequent  parts  of  this  work,  in  which  I  shall  have 
occasion  to  instance  various  animal  and  vegetable  co- 
lours, produced  solely  by  the  contact  of  vital  or  atmos- 
pheric air;  and  some  others,  which,  when  given  by  dye- 
ing or  calico  printing  to  wool,  silk,  cotton,  Sec.  though 
unable  to  sustain  a  single  day's  exposure  to  the  sun  and 
air  without  manifest  injury,  were  found  to  receive  none 
frem  the  action  of  acids  of  considerable  strength,  but, 
on  the  contrary,  were  in  some  degree  preserved  by  being 
wetted  with  them,  and  especially  with  the  citric  acid. 
But  the  same  colours,  if  covered  with  linseed  oil,  were 
found  to  decay  more  quickly  from  exposure  to  the  sun 
and  air,  than  if  uncovered.  These  colours  therefore 
could  not  owe  their  decays  to  the  contact  or  combina- 
tion of  oxygene,  because  they  were  not  only  unhurt, 
but  benefited  by  its  agency  in  the  citric,  and  other  acids 
containing  it;  and  also  because  they  were  soonest  im- 
paired when  secluded  from  it  by  a  covering  of  linseed 
oil.  Probably  the  decay  of  these  colours  was  occasioned 

*  Oxygene  is  also  absolutely  necessary  to  produce  the  blue  colour 
of  Prussian  blue,  and  the  black  colour  of  ink.  These  facts  are  too 
notorious  to  require  proof. 


48  Philosophy  of  Permanent  Colours. 

by  a  loss  of  at  least  some  part  of  the  oxygene,  necessary 
to  their  existence,  and  which  the  linseed  oil  assisted  in 
depriving  them  of,  by  its  known  affinity  therewith. 

In  forming  systems,  w^e  are  apt  to  draw  general  con-' 
elusions  from  partial  views  of  i^icts.  And  this  even  M. 
Berthollet  seems  to  have  done,  not  only  in  ascribing 
the  decays  of  vegetable  and  animal  colours,  exclusively 
to  effects  similar  to  those  of  combustion,  but  also  in  re- 
presenting the  oxy-muriatic  acid  as  an  accurate  test  or 
measure  for  anticipating,  in  a  few  minutes,  the  changes 
which  these  colours  are  liable  to  suffer,  by  long  expo- 
sure to  the  action  of  sun  and  air;  for  though  it  should 
be  true  that  the  oxygenated  muriatic  acid,  in  weakening 
or  destroying  colours,  gives  up  to  them  more  or  less  of 
the  oxygene,  which  it  is  supposed  to  have  received  from 
manganese;  and  that,  by  this  new  combination  of  oxy- 
gene, those  affinities  for  particular  rays  of  light  upon 
which  their  colours  depend,  are  liable  to  be  destroyed; 
it  is  nevertheless  true,  that  the  changes  of  colour  so 
produced  are  no  certain  indication  of  those  which  the 
combined  injluence  of  light  and  air  will  occasion  upon 
colours  in  general;  there  being,  as  I  have  already  ob- 
served, and  as  I  shall  more  fully  explain  hereafter, 
several  colours  which  are  very  speedily  destroyed  by 
the  latter  of  these  causes,  though  they  resist  the  action 
of  the  oxy-muriatic  acid,  even  longer  than  the  best  co- 
lours given  to  printed  calicos. 

M.  Berthollet  well  knows,  since  nobody  has  contri- 
buted more  to  ascertain,  how  much  the  properties  of 
oxygene  are  diversified  by  each  particular  basis  to  which 
it  unites;  and  it  does  not  therefore  seem  warrantable  to 
imagine,  that  its  action  would  not  be  modified^  as  well 
as  increased,  by  a  basis  so  powerful  as  that  of  the  com« 
mon  muriatic  acid;  or  that  the  united  properties  of  bothy 
should  exactly  represent  or  resemble  those  of  atmos- 


Philosophy  of  Permanent  Colours*  49 

pheric  air  upon  colours,  any  more  than  they  do  in  the 
lungs,  where,  instead  of  supporting  life,  when  respired, 
they  would  instantly  destroy  it. 

Ten  years  after  I  had  published  the  preceding  ob- 
servations, M.  BerthoUet,  in  the  new  edition  of  his 
'*Elemens  de  Teinture,"  (between  pages  131  and  147 
of  the  first  volume)  recapitulated  those  parts  of  his 
former  edition,  which  relate  to  this  subject;  and  for, 
doing  so,  he  assigned  the  following  motive,  viz.  **  par- 
ceque  Bancroft,  dont  Pautorite  est  pour  nous  d^un  grand 
poids,  a  pretendu  refuter  la  theorie  qui  y  est  etablie,  et 
que  nous  desirous  de  mettre  en  etat  de  peser  ses  raisons, 
et  les  motifs  de  notre  opinion."  He  afterwards  (p.  147., 
and  seq.)  notices  some  of  my  objections  to  his  theory; 
and  particularly  that  wherein  I  asserted,  that  colouring 
matters  suffer,  by  the  action  of  acids,  and  other  sub- 
stances, alterations  which  cannot  be  compared  to  com- 
bustion; to  which  he  answers,  "  mais  il  n'est  question 
dans  les  explications  precedentes,  que  de  I'espece  d'al-^^ 
teration  qui  depend  de  Paction  de  Toxigene."  This  an^, 
swer,  were  I  not  fully  convinced  of  M.  Berthollet's 
perfect  candour  and  regard  for  truth,  would  seem  to  be 
either  an  evasion,  or  a  mere  petitio  principii:  and  it 
certainly  has  the  effect,  of  at  least  greatly  narrowing  the 
ground  of  our  dispute;  for  I  have  never  contended  that 
oxygene  assisted  by  light,  does  not  iti  some  cases  injure 
colours  in  the  way  which  M.  BerthoUet  supposes,  i.  e. 
by  combining  with  the  hydrogene  of  the  colouring  mat- 
ter, &c.;  though  I  have  objected  to  what  seems  to  have 
been  his  opinion,  that  this  was  the  only  way  in  which 
the  fading  or  decaying  of  colours  ought  to  be  explained; 
and  considering  the  very  opposite  effects  of  light  in  re- 
gard to  oxygene,  which  have  been  recently  stated  (and 
which  M.  BerthoUet  seems  to  have  overlooked)  it  is 
impossible  for  mc  not  to  persist  in  that  objection.  It 

Vol.  I.  G 


50  Philosophy  of  Permanent  Colours. 

therefore  still  remains  for  us  to  ascertain,  and  distinguish 
the  particular  cases  in  which  oxygene,  assisted  by  light, 
injures  colours,  by  combining  with  the  hydrogene  of 
their  respective  colouring  matters;  but  even  if  this  were 
done,  I  should  never  be  convinced  that  these  matters 
had  naturally  contained  ready  formed  black  charcoal^ 
and  that  the  degradation  of  the  faded  or  injured  colour, 
resulted  from  a  greater  manifestation  and  predominance 
of  this  charcoal,  with  its  supposed  naturally  black  co- 
lour. 

M.  Berthollet  next  adverts  to  my  objection  that  oxy- 
gene, far  from  destroying  colours  generally^  is  neces- 
sary to  the  existence  of  some  of  them,  as  e.  g.  of  indigo. 
And  to  this  he  answers,  *'  n'est-ce  pas  ce  que  Ton  a  dit? 
mais  I'on  a  distingue  les  cas  ou  il  devient  un  element 
de  la  couleur,  et  ceux  ou  son  action  devient  destruc- 
tive." An  answer  which  leaves  us  still  to  ascertain  and 
distinguish  the  numerous  colouring  matters,  of  which 
oxygene  is  admitted  to  be  an  essential  constituent,  and 
which,  from  that  circumstance,  will  be  most  suscepti- 
ble of  being  injured,  by  a  deprivation  of  oxygene,  rather 
than  by  any  addition  of  it;  and  even  after  this  distinc- 
tion shall  have  been  made,  it  will  not  follow,  as  a  neces- 
sary consequence,  that  the  other  remaining  colours  are 
not  liable  to  suffer  by  effects  very  different  from  those 
of  combustion. 

Next  in  order,  M.  Berthollet  notices  my  objection  to 
his  ascribing  the  degradation  oi faded  colours,  to  a  pre- 
dominance of  charcoal,  since  many  substances  contain 
large  proportions  of  it,  without  having  any  such  colour 
as  has  been  ascribed  to  its  excess;  and  since  the  colour 
of  charcoal  itself,  results  only  from  an  oxygenation  of 
its  basis.  To  this  he  answers,  that  without  entering 
upon  a  discussion  of  my  opinion  on  this  point,  "  il  s'agit 
seulement  de  S9avcir,  si  dans  les  circonstances  dont  il 


Philosophy  of  Permanent  Colours*  51 

est  qaestion,  le  changement  de  couleur  n'a  pas  de  I'ana- 
logie  avec  celui  que  Ton  observe,  lorsque  I'on  distille 
une  substance  vegetale:"  and  he  seems  to  imagine 
(erroneously)  that  I  had  conceived  the  free  access  of 
the  oxygene  of  the  atmosphere,  to  be  necessary  to  the 
browning  of  vegetable  matter  in  that  process,  where 
there  is  otherwise,  a  sufficiency  of  oxygene.  He  next 
observes,  that  I  had  erred  in  supposing  that  his  opinion 
was  founded  solely  upon  experiments  made  with  the 
brown  colouring  matter  of  unbleached  linen.  But  it  will 
have  been  seen,  that  I  only  mentioned  this  as  the  matter 
upon  which  they  ^'^  were  principally  made,'''' 

And,  finally,  in  regard  to  my  objection  to  his  assum- 
ing the  action  of  the  oxy- muriatic  acid  upon  dyed 
colours,  to  be  an  exact  indication  and  measure  of  that 
which  they  would  suffer  by  exposure  to  the  sun  and 
air,  he  observes  that  he  did  not  find  in  my  work,  an  ac- 
count of  the  experiments  which  I  had  announced,  as 
sufficient  to  prove  that  the  effects  of  the  oxy-muriatic 
acid,  are  sometimes  at  variance  w  ith  those  of  the  oxy- 
gene of  the  atmosphere.  For  this  last  observation  there 
may  have  been  some  little  foundation;  but  my  readers 
will  soon  find  it  removed.  I  had,  indeed,  occasionally 
noticed  some  of  these  experiments,  though  not  collec- 
tively; and  others  were  intended  to  be  also  mentioned 
occasionally,  in  the  second  volume. 

M.  BerthoUet  next  admits,  that  in  comparing  the 
effects  of  the  oxy-muriatic  acid,  with  those  of  the  oxy- 
gene of  the  atmosphere,  it  is  necessary  to  take  into  con- 
sideration the  greater  condensation  of  the  oxygene  in  the 
former,  together  with  "  V action  particuliere  de  Vacide 
Muriatique;^''  which,  to  my  understanding,  he  certainly 
did  not  do  in  regard  to  the  latter;  and  his  not  doing  it, 
was  the  chief  foundation  of  my  objection.  Even  in  his 
last  edition  (torn.  i.  p.  68)  when  treating  of  these  effects, 


52  Philosophy  of  Permanent  Colours. 

of  the  oxy-muriatic  acid  upon  colours,  he  says  "  il  agit 
alors  par  Voxigene  quHl  abandonne^  et  par  consequent 
son  action  ne  differe  que  par  Pintensite,  de  celle  de  Pair 
atmospherique;^^  so  that  even  in  this  last  edition,  the 
particular  action  of  the  mui'iatic  acid  is  completely,  and 
as  M.  Berthollet  now  admits,  improperly  overlooked. 
He  admits  also,  at  p.  149,  that  it  is  necessary  to  distin- 
guish between  the  effects  produced  by  the  oxy-muria- 
tic acid,  when  it  completely  discharges  or  extinguishes 
all  colour,  and  those  due  to  the  combination  of  its  oxy- 
gene,  with  the  hydrogene  of  the  colouring  matters.  I 
do  not,  however,  believe,  that  there  is  any  such  differ- 
ence in  its  action,  or  that  it  ever  relinquishes  any  oxy- 
gene  to  combine  with  the  hydrogene  of  the  colouring 
matter  in  question;  but  that  it  destroys  colours,  by  a 
power  peculiar  to  itself,  and  inexplicable  by  any  of  its 
sensible  qualities;  a  power  manifested  by  effects  the 
very  reverse  of  combustion,  since  that  highly  combusti- 
ble substance  cotton,  is  bleached  and  rendered  perfectly 
white  by  it,  instead  of  being  made  brown  or  black,  as 
it  would  be,  if  its  mode  of  action  were  such  as  is  here 
supposed. 

M.  Berthollet  afterwards  brings  this  discussion  to  a 
conclusion,  by  the  following  partial  concession,  at  p. 
150,  viz. 

"  Si  nous  avons  cru  pouvoir  refuter  les  objections 
de  Bancroft,  sur  la  cause  au  moins  la  plus  ordinaire  de 
la  degradation  des  couleurs  par  I'air  et  la  lumiere,  nous 
convenons  que  les  consequences  de  I'opinion  que  nous 
tachons  de  maintenir,  n^auraient  pas  du  etre  etendues 
aux  phenomenes  que  nous  allons  examiner,  quoiqu'on  ne 
I'eiit  fait  qu'avec  beaucoup  de  reserve,  et  sans  sortir 
des  bornes  d'une  simple  conjecture:"  and  he  then  pro- 
ceeds to  an  examination  of  the  phenomena,  to  which 
his  doctrine  on  this  subject  ought  not  to  have  been  ex- 


Philosophy  of  Permanent  Colours,  So 

tended.  Of  these,  the  principal  relates  to  the  yellow 
colour  produced  upon  wool,  silk,  and  other  animal  sub- 
stances, by  the  nitric  acid;  of  which  I  haVe  already 
given  what  appears  to  be  the  only  true  explanation  at 
p.  28. 

If  I  have  sometimes  thought  it  my  duty  to  contest 
the  opinions  of  M.  Berthollet,  I  have  always  done  it  re- 
luctantly, and  I  can  feel  no  pleasure  in  prolonging,  un- 
necessarily, a  controversy  with  one,  for  whose  decisions 
I  feel  so  much  deference,  even  where  I  believe  it  might 
be  done  with  advantage  on  my  side;  I  should,  therefore, 
here  terminate  our  discussion,  were  it  not  incumbent 
on  me  to  state  certain  facts,  which  prove  that  the  effects 
of  the  oxy-muriatic  acid  upon  particular  colours,  are 
not  an  indication  or  measure  of  those  changes,  which 
would  take  place  in  the  same  colours,  by  exposure  to 
the  sun  and  air;  and  of  which  facts,  M.  Berthollet  com- 
plains that  he  did  not  find  a  statement  in  the  volume 
formerly  published. 

In  the  introductory  part  of  my  present  volume,  I  have 
noticed  the  subsisting  opposite  opinions,  concerning  the 
nature  and  constitution  of  the  substance,  called  acide 
muriatique  oxigene,  by  the  French  chemists,  and  oxy- 
muriatic  acid  by  the  British;  and  which  Sir  H.  Davy 
has  lately  denominated,  chlorine,  M.  Berthollet  and 
others,  who  believe  oxygene  to  be  one  of  its  constituent 
parts,  suppose  that  in  bleaching  or  destroying  colours, 
it  acts  by  giving  up  to  them  its  oxygene.  Scheele  had 
imagined  that  it  did  this,  by  combining  with  phlogiston^ 
which  was  then  thought  to  be  the  most  important  part 
of  colouring  matters;  and  Davy,  who  like  Scheele,  con- 
siders his  chlorine  as  a  simple  or  decompounded  sub- 
stance,  says  (p.  243.)  that  it  decomposes  water  by  a 
double  affinity;  **  that  of  the  hydrogene  for  chlorine,  and 
that  of  the  colouring  matters  for  oxygene;"  to  which 


54  Philosophy  of  Permanent  Colours. 

last  he  ascribes,  like  M.  Berthollet,  the  destructive  ac- 
tion of  chlorine  upon  colours,  though  he  derives  the 
oxygene  from  a  different  source.  But  if,  as  is  here  sup- 
posed, the  destruction  of  colours  by  the  oxy-muriatic 
acid  resulted  solely  from  the  oxygene,  which  it  either 
relinquishes,  or  separates  from  water,  its  effects  on  co- 
lours ought  to  resemble  those  of  the  nitric  acid,  when 
the  quantity  of  oxygene  which  they  severally  aflford,  or 
put  into  action,  is  the  same,  and  the  effect  of  each 
ought  to  be  proportioned  to  the  degree  of  acidity  in  the 
destroying  agent.  Many  experiments  have,  however, 
convinced  me,  that  few  things  are  more  unlike,  than 
the  several  efl'ects  of  the  oxy-muriatic,  and  nitric  acids, 
upon  colours  giving  by  dyeing,  Sec.  A  very  few  of  these 
experiments  will  suffice. — I  put  into  a  small  phial,  cut- 
tings from  three  skeins  of  cotton  yarn,  which  had  been 
dyed,  and  sent  to  me  by  M.  Chaptal,  before  he  was 
called  from  his  chemical  labours  to  those  of  a  minister 
of  state.  One  these  had  received  the  Turkey  red,  ano* 
ther  the  nankeen  bufl',  from  an  oxide  of  iron,  and  the 
third  a  black,  as  I  believe,  from  madder  and  galls,  ap- 
plied upon  the  basis  of  iron,  dissolved  by  the  pyrolig- 
neous  acid.  Upon  these  colours  I  poured  oxy-muriatic 
acid,  which  had  been  prepared  by  Mr.  Accum,  and 
kept  secluded  from  light.  Its  acidity  was  so  slight  as  to 
be  hardly  perceptible  to  the  taste,  and,  I  believe,  it 
might  have  been  put  into  the  eye,  without  causing  much 
pain.  I  found,  however,  that  in  less  than  two  minutes, 
the  colour  of  the  Turkey  red  was  much  impaired,  and 
in  five,  the  yarn  throughout  the  greater  part  of  its  sur- 
face had  become  white,  without  passing  through  any 
intermediate  colour:  and  at  the  end  of  half  an  hour,  but 
a  very  few  specks  of  red,  less  than  a  pin's  head,  were 
perceptible.  The  buff  colour  at  that  time  was  found  to 


Philosophy  of  Permanent  Colours.  55 

have  acquired  a  little  body,  and  the  black  to  have  lost 
a  little,  but  without  ceasing  to  be  still  a  good  black. 

At  the  same  time,  I  put  other  cuttings  of  the  same  co- 
lours into  another  phial,  and  poured  upon  them  undiluted 
aqua  fortis,  as  prepared  for  the  scarlet  dyers;  and  1  found 
that  in  a  single  minute  the  black  which  had  withstood  the 
oxy-muriatic  acid,  was  changed  to  a  buff  colour,  result- 
ing solely  from  the  ferruginous  basis  with  which  it  had 
been  dyed;  and  that  the  Turkey  red  began  to  exhibit  the 
appearance  of  a  scarlet^  inclining  to  the  orange;  and  this 
last,  (of  a  lively  tint,)  became  apparently  its  settled  co- 
lour, at  the  end  of  an  hour,  when  the  buff,  by  acquiring 
more  oxygene,  was  considerably  raised.  Here,  then,  was 
a  very  great  diversity  between  the  effects  of  the  nitric 
and  the  oxy-muriatic  acids,  in  no  degree  according,  or 
proportionate  to  their  degrees  of  acidity;  that  of  the  nitric 
acid  being,  I  think,  at  least  fifty,  and,  perhaps,  one  hun- 
dred times  greater  than  that  of  the  oxy-muriatic  acid, 
(which  being  tasted,  at  the  time  when  its  action  upon  the 
Turkey  red  was  strongest,  and  when,  according  to  Da- 
vy's opinion,  it  must  have  already  decomposed  water,  had 
not,  to  my  taste,  acquired  any  greater  degree,  of  acidi- 
ty.) and  yet  the  former,  could  only  change  the  complex- 
ion of  the  Turkey  red  to  a  bright  orange,  (probably  by 
imparting  oxygene  to  it)  while  the  latter  (not,  as  I  con- 
ceive, by  any  such,  or  other  addition,  but  by  a  complete 
decomposition  J  had  at  once  annihilated  all  the  colour, 
(leaving  the  cotton  yarn  white)  as  fast,  and  as  far,  as  the 
decomposition  took  place;  and  this  without  any  interme- 
diate tint,  which  would  not  have  been  the  case  if  the  ef- 
fect of  the  oxy-muriatic  had,  as  M.  Berthollet  supposes, 
resembled  combustion.  And,  on  the  other  hand,  the 
black,  on  which  the  oxy-muriatic  acid  could  make  but 
a  very  slight  impression,  was  completely  destroyed,  (ex- 
cepting the  colour  of  its  ferruginous  basis)  by  the  nitric 


56  Philosophy  of  Permanent  Colours. 

acid.  Not  unnecessarily  to  multiply  instances  of  these 
unequal  efTects,  I  will  barely  mention,  what  will  be  stated 
more  fully  hereafter,  that  this  slightly  acid  chlorine,  or 
oxy-muriatic  acid,  was,  by  repeated  experiments,  found 
to  produce  more  destructive  effects  on  the  fine  purple  of 
the  Buccinum  lapillus,  than  aqua  foitis,  or  the  strong 
undiluted  oil  of  vitroil.  Indeed,  when  I  consider  how 
generally  and  how  powerfully  the  oxy-muriatic  acid  de- 
stroys animal  and.  vegetable  colours,  whilst,  from  its  very 
slight  acidity,  it  cannot  be  supposed  capable  of  either  re- 
linquishing, or  separating  from  water,  any  portion  of 
oxygene  at  all  adequate  to  such  effects,  or  in  any  degree 
comparable  to  the  oxygene  of  the  nitric  acid,  (and  which 
the  latter  readily  gives  up,  without  producing  any  equal- 
ly destructive  effect  on  colours,)  it  seems  to  me  as  un- 
reasonable, to  ascribe  this  powerful  agency  of  the  former, 
to  any  portion  of  oxygene  which  it  can  possibly  brings 
into  action^  as  it  would  be  to  impute  the  death  of  a  man, 
poisoned  by  two  or  three  grains  of  the  corrosive  subli- 
mate of  mercury,  to  the  single  grain  of  chlorine  or  oxy- 
muriatic  acid,  which,  combined  with  quicksilver,  con- 
stitutes this  sublimate. 

If  this  chlorine  be,  as  Sir  H.  Davy  supposes,  a  simple 
elementary  substance,  it  must  produce  its  singularly  de- 
structive effects  on  colours,  principally  at  least,  by  a 
power  peculiar  to  itself,  (which  probably  is  a  decompo- 
sing power,)  and  if  it  be,  as  M.  BerthoUet  supposes,  a 
compound,  (of  oxygene  and  muriatic  acid)  its  peculiar 
energies  must  result  from  its  composition;  from  the  com- 
bined agency  of  its  constituent  parts,  and  not  from  the 
action  of  either  separately,  as  has  been  supposed.  And  it 
may  be  presumed,  that  the  same  peculiar  decomposing 
power,  which  enables  the  oxy-muriatic  acid  to  annihilate 
Colours  with  such  extraordinary  celerity,  enables  it  also 
(by  decomposition)  to  weaken  and  injure  the  texture  of 


Philosophy  of  Permanent  Colours.  57 

wool  and  other  animal  fibres,  as  it  is  known  to  do,  in  a 
much  greater  degree  than  the  incomparably  stronger  sul- 
phuric and  nitric  acids. 

It  now  only  remains  for  me  to  mention  a  few  of  the  in- 
stances within  my  knowledge,  proving  that  the  action  of 
the  oxy-murialic  acid  upon  colours,  is  not  an  indication 
or  measure  of  that  which  they  would  suffer,  by  exposure 
to  the  sun  and  air;  and  these  instances  I  will  select  from 
an  experiment,  which  was  made  carefully,  and  so  recent- 
ly as  the  8th  of  July,  1812;  when  I  put  into  an  empty^ 
glass-stopped  phial,  the  following  colours,  upon  separate 
bits  of  muslin,  viz. 

1st.  A  fast  madder  red  dyed  topically,  by  an  eminent 
calico  printer,  upon  a  basis,  from  acetate  of  alumine,  ap- 
plied by  the  block. 

2d.  A  fast  yellow,  dyed  from  weld  upon  the  same  basis, 
by  the  same  calico  printer. 

3d.  A  fast  yellow,  dyed  upon  the  same  basis,  from 
quercitron  bark. 

4th.  A  fine  durable  purple  produced  by  the  colouring 
matter  of  the  buccinum  lapillus,  of  which  a  full  account 
will  be  given  in  the  proper  place. 

5th.  A  logwood  purple  produced  by  mixing,  with  a 
strong  decoction  of  that  wood,  as  much  muriate  of  tin, 
as  rendered  the  former  slightly  acid,  and  after  thickening 
the  mixture  with  gum  arable,  applying  it  in  spots  to 
muslin,  which,  after  being  properly  dried,  was  washed 
with  soap  and  water. 

6th.  A  full  bright  yellow  produced  from  a  similar  de- 
coction of  the  quercitron  bark,  rendered  slightly  acid  by 
an  admixture  of  nitro- muriate  of  tin,  made  with  two  parts 
of  nitric,  to  one  part  of  muriatic  acid,  gummed,  and  topi- 
cally applied  in  the  same  manner  as  the  logwood  purple, 
and  in  like  manner  dried,  and  afterwards  washed. 

Vol.  I.  H 


58  Philosophy  of  Permanent  Colours, 

7th.  A  similar  yellow  made  from  the  quercitron  bark, 
only  substituting  murio-sulphate  of  tin,  for  the  nitro- 
muriate.  Upon  these  colours  I  poured  oxy-muriatic  acid, 
with  which  Mr.  Accum  had  recently  supplied  me,  (and 
which  I  had  kept  secluded  from  the  light,)  until  the  phial 
was  full;  after  which,  in  less  than  two  minutes,  I  found 
that  the  bits  of  muslin,  with  the  madder^  weld,  and  quer- 
citron, colours  dyed  upon  the  aluminous  basis,  were  be- 
come perfectly  white,  by  a  complete  extinction  of  their 
several  colours.  Whilst  the  logwood  purple,  that  from  the 
the  buccinum,  and  the  quercitron  yellows,  with  solutions 
of  tin,  were  not  apparently  changed.  But  in  about  five 
minutes  the  logwood  purple  appeared  to  be  losing  body, 
as  did  the  quercitron  yellows  soon  after;  and  a  similar  ef- 
fect soon  became  evident  in  the  shell  purple. 

In  about  fifteen  minutes,  from  the  time  when  these  co- 
lours were  immersed  in  the  oxy-muriatic  acid,  the  log- 
wood purple  had  nearly  disappeared;  and  this  was  the 
case  of  the  quercitron  yellows  in  about  three  minutes  af- 
terwards, and  of  the  shell  purple  about  two  minutes  later; 
excepting  that  a  part  of  the  latter,  as  well  as  a  part  of  one 
of  the  yellows  given  with  tin,  had  each  preserved  a  por- 
tion of  colour,  by  having  been  protected,  by  other  bits  of 
muslin,  from  the  sun's  rays,  which,  as  the  sky  was  clear, 
had  had  free  access  to  the  phial  containing  them,  at  the 
window  where  this  experiment  was  made;  a  fact  which 
manifested  the  influence  of  solar  light,  in  promoting  the 
destructive  action  of  the  oxy-muriatic  acid,  on  the  colours 
in  question. 

It  is  here  to  be  recollected,  that  the  three  first  mention- 
ed colours,  dyed  upon  the  aluminous  basis,  would  have 
resisted  the  action  of  sun  and  air  for  two  or  three  months, 
and  the  madder  for  a  much  longer  time,  and  yet  they 
were  completely  destroyed  in  an  eighth  part  of  the 
time  which  was  required  to  destroy  the  logwood  purple, 


Philosophy  of  Permanent  Colours.  59 

and  the  yellows  with  tin;  neither  of  which  could  have 
been  exposed  to  the  sun  and  air  for  a  single  week,  with- 
out becoming  of  a  faded  brown.  It  is  also  worthy  of  ob- 
servation, that  the  Tyrian,  or  shell  purple,  was  destroyed 
by  the  oxy-muriatic  acid,  almost  as  soon  as  the  logwood 
purple  and  quercitron  yellows  last  mentioned,  though  it 
would  have  resisted  the  sun  and  air,  probably  fifty  times 
longer  than  either  of  them. 

The  property  by  which  certain  matters  decompose  so- 
lar light,  reflecting  or  transmitting  some,  and  absorbing 
other  rays,  so  as  to  produce  the  sensations  or  perceptions 
of  particular  colours,  often  depends  upon  precise,  and 
nice  proportions  in  the  constituent  parts  of  these  colour- 
ing matters,  which  proportions  may  be  altered,  and  the 
colours  resulting  from  them  destroyed  or  changed  by  va- 
rious means,  acting  even  in  opposite  ways. 

Oxygene  from  its  ubiquity,  as  a  part  of  the  atmosphere, 
and  its  powerful  agencies,  co-operates  in  almost  all  the 
the  changes  which  take  place  on,  or  above  the  surface  of 
tlie  earth,  and  especially  in  those  connected  with  either 
the  production  or  the  destruction  of  colours,  and  its  pre- 
sence as  a  constituent  part  of  colouring  matters,  seems  to 
be  essentially  necessary  to  those  peculiar  attractions,  or 
affinities,  which,  by  their  effects  upon  the  rays  of  light, 
occasion  the  perceptions  or  sensations  of  colour.  This 
will  be  abundantly  proved,  and  elucidated  by  the  highly 
instructing  and  interesting  facts  to  be  stated  hereafter, 
concerning  indigo. 

But  though  combinations  of  oxygene  in  certain  propor- 
tions, are  necessary  to  the  existence  of  most,  if  not  of  all, 
colours,  an  excess  of  it  may  obstruct  all  manifestation  or 
appearance  of  colour,  as  completely  as  the  total  absence  of 
it  does,  in  regard  to  indigo.  Of  this  a  signal  instance,  and  il- 
lustration, will  be  found  hereafter,  in  the  colourable  matter 
of  the  Buccinum  producing  the  ancient  or  shell  purple;  and 


60  Philosophy  of  Permanent  Colours, 

this  last,  as  I  have  already  intimated,  will  moreover  afford 
a  most  curious  demonstration,  and  exemplification,  of 
the  influence  of  solar  light,  in  one,  and  that  the  most 
common  of  the  ways  in  which  it  acts  upon  colouring 
matters;  I  mean  that  of  separating  or  causing  an  abstrac- 
tion of  their  oxygene:  and  it  will  be  readily  perceived  that 
these  colourable  matters  (of  indigo,  and  of  the  shell  pur- 
ple,) become  the  more  interesting  and  instructive,  by 
reason  of  their  opposite  conditions  and  analogies. 

To  ascertain  by  well-directed  experiments,  made  upon 
the  several  dyeing  drugs,  and  the  colours  produced  by 
them,  with  their  usual  or  most  suitable  mordants,  or 
bases,  in  which  of  the  ways  lately  mentioned,  or  in  what 
other  ways,  their  several  colours  are  most  liable  to  suffer 
injuries  or  decays,  would  doubtless  contribute  greatly  to 
improve  the  art  of  dyeing,  by  enabling  us  to  employ  the 
means  proper  for  obviating  or  correcting  their  respective 
defects,  so  as  to  render  colours  permanent,  which  have 
hitherto  been  deemed  fugitive;  and,  perhaps,  increase  the 
durability  and  beauty,  even  of  those  which  are  consider- 
ed as  permanent. 

With  this  persuasion  I  have,  at  different  times,  pro- 
jected various  experiments,  calculated  to  ascertain  the 
effects  of  the  sun's  rays,  upon  colouring  matters,  in  all 
their  usual  combinations,  when  placed  in  vacuo,  and  also 
when  immersed  in  the  several  kinds  of  air,  and  in  alcohol, 
unctuous,  and  essential  oils,  diluted  acids,  and  alkalies,  in 
prder  to  ascertain  the  effects  of  these  different  agents  or  ap- 
plications, upon  the  several  colours;  and  also  as  far  as  might 
be  practicable,  to  discover  what  each  had  either  lost  or 
gained  by  such  treatment.  But  from  the  number  and  va- 
riety of  my  other  unavoidable  avocations,  and  interrup- 
tions, my  progress  in  these  experiments  (excepting  a  few 
which  will  be  mentioned  in  their  proper  plact  s)  has  not 
been  sufficient  to  warrant  those  ultimate  conclusions, 


Philosophy  of  Permanent  Colours.  61 

which  could  only  be  safely  and  properly  drawn,  after  an 
examination  and  comparison  of  the  whole;  and  as  I  may 
not  live  or  find  leisure  to  execute  the  whole,  I  can  only  re- 
commend the  subject  to  those  who  may  have  sufficient 
time  and  qualifications  for  a  due  investigation  of  it. 

Until  further  discoveries,  therefore,  shall  have  been 
made,  I  consider  myself  as  only  authorized  to  conclude, 
that  the  permanent  colours  of  matter  do  not  depend  upon 
the  thicknesses,  sizes,  or  densities  of  its  parts  or  particles, 
but  upon  certain  affinities  or  attractions,  physical,  or  che- 
mical, by  which  it  is  disposed  and  enabled  to  absorb  and 
conceal  some  of  the  rays  of  light,  and  to  reflect  or  trans- 
mit other  rays,  producing  the  sensations  or  perceptions 
of  particular  colours;  and  that  to  the  existence  or  energy 
of  these  affinities,  or  attractions,  certain  portions  of  oxy- 
gene  are  generally  necessary,  as  a  constituent  part  of 
colouring  matters;  and  these  portions  may  in  some  in- 
stances be  increased,  and  in  others  diminished,  by  the 
influence  of  radiant  matter^  or  solar  light,  which  may 
thereby  contribute  to  the  production  of  some,  and  the  de- 
struction of  other  colours. 

Should  I  be  desired  to  assign  a  reason  or  cause  for 
these  affinities,  and  their  connexion  with  particular  pro- 
portions of  oxygene,  I  can  only  answer  with  M.  de  Buf- 
fon,that  they  who  require  the  reason  of  a  general  effect ^ 
do  not  consider  the  infinite  extent  of  nature's  operations, 
nor  the  confined  limits  of  human  understanding. 


6i  Philosophy  of  Permanent  Colours. 

CHAPTER  II. 

Of  the  Composition  and  Structure  of  the  Fibres  of 

fFool,  Silk^  Cotton,  and  Linen, 

"  Ubi  natura  desinit  nobis  incipiendum.'* 

Before  I  treat  of  the  communication  or  production 
of  colours  by  dyeing  or  calico  printing,  it  will  be  proper 
to  inquire  concerning  the  particular  natures  and  differ- 
ences of  wool,  silk,  cotton,  and  linen,  upon  which  these 
operations  are  usually  performed.  The  two  first  are  ani- 
mal, and  the  latter  are  vegetable  substances,  differing  from 
each  other  in  their  constituent  parts  and  chemical  proper- 
ties, as  well  as  in  structure  and  organization.  M.  Ber- 
thoUet  has  greatly  contributed  towards  ascertaining  their 
chemical  differences,  which  seem  principally  to  depend 
upon  a  much  larger  proportion  of  nitrogene,  and  also  of 
hydrogene,  in  the  animal,  than  in  the  vegetable  matters: 
and  as  the  nitrogene  and  hydrogene  readily  assume  an 
elastic  form,  the  wool,  hair,  and  silk,  in  which  they 
abound,  have  less  adhesion  between  their  constituent 
parts,  than  that  which  exists  between  those  of  cotton, 
and  linen,  and  they  are,  therefore,  more  strongly  disposed, 
than  the  latter,  to  combine  with  other  substances,  when 
brought  into  contact  with  them;  and  it  is,  I  believe, 
partly  in  consequence  of  this  disposition  that  wool,  hair, 
and  silk,  manifest  stronger  affinities  or  attractions  for  co- 
louring matters  generally,  than  cotton,  and  linen.*  They 

*  <r.  g.  Cotton  and  linen  will  neither  of  them  receive  any  colour 
by  the  same  preparation,  and  in  the  same  liquor,  which  dyes  wool 
or  woollen  cloth  scarlet.  This  is  every  day  seen  by  the  cotton 
edges  with  which  some  some  sorts  of  cloth  are  wove,  which  re- 
main white  after  the  rest  of  the  cloth  is  become  scarlet.  M.  Dufey 
caused  a  piece  of  cloth  to  be  manufactured,  of  which  the  chain  was 
wool,  and  the  woof  cotton.  This  was  afterwards  fulled,  that  both 


Philosophy  of  Permanent  Colours.  63 

are  also  more  readily  decomposed,  or  injured  by  acids, 
alkalies,  and  other  chemical  agents,  which  ought  there- 
fore to  be  very  sparingly  used  in  the  dyeing  of  animal  sub- 
stances:  it  being  found  that  the  sulphuric,  nitric,  and 
muriatic  acids  readily  decompose  wool,  hair,  and  silk, 
and  at  the  same  time  destro} ,  or  greatly  weaken  the  tex- 
ture and  connexion  of  their  several  fibres;  and  that  alka- 
lies prove  equally  injurious,  by  combining  with  th*  m: 
though  silk  is  indeed  not  so  liable  to  be  acted  upon  in 
these  ways,  because  it  partakes  in  some  degree  of  the 
vegetable  nature.  Animal  fibres,  also,  contain  more  oil 
and  less  of  the  basis  of  charcoal  than  the  vegetable. 

It  is  from  the  superior  chemical  affinities,  or  attractions 
existing  in  wool,  hair,  and  silk,  for  colouring  matters, 
that  the  facilities  with  which  these  substances  receive, 
and  permanently  retain  colours,  principally  result;  though 
something  is  doubtless  to  be  ascribed  to  the  differences 
of  conformation,  existing  between  their  fibres  and  those 
of  cotton  and  linen,  which  I  shall  notice  under  their  several 
heads. 

Article  I. — OfWooL 
The  value  of  this  substance,  and  its  fitness  for  the  dif- 
ferent kinds  of  manufacture,  depend  in  a  great  degree  on 
the  length  and  fineness  of  its  fibres;  of  which  ample  infor- 
mation may  be  found  in  a  Memoir  written  by  M.  d'Au- 
benton,  and  printed  among  those  of  the  Royal  Academy 
of  Sciences,  for  the  year  1779.  Wool  is  liable  to  great 
variations  in  quality,  not  only  from  differences  in  each 
particular  race  or  breed  of  the  sheep,  from  which  it  is 
taken,  but  also  of  the  parts  of  the  body  to  which  it  has 
adhered;  that  which  covers  the  tails,  thighs,  and  bellies, 

might  be  brought  into  a  similar  state  of  preparation;  and  the  cloth 
being  then  dyed  by  the  usual  process,  the  woollen  threads  contain- 
ed in  it  received  a  good  scarlet,  whilst  the  cotton  remained  white. 


64         '     Philosophy  of  Permanent  Colours. 

being  always  coarser,  and  less  susceptible  of  receiving 
colours  by  dyeing.  It  also  frequently  suffers  in  quality,  and 
in  colour,  by  the  diseases  to  which  sheep  are  liable;  the 
most  healthy  of  the  same  flock,  always  affording  wool 
which  is  of  a  better  quality  than  that  of  the  unhealthy; 
and  which  has  also  a  greater  affinity  for  colouring  matters, 
and  imbibes  them  more  copiously  by  dyeing. 

Wool  is  naturally  covered  by  an  unctuous  substance, 
which  probably  is  destined  to  secure  it  from  the  injurious 
effects  of  moisture.  This  substance  (called  yolk  by  the 
English,  and  suint  by  the  French,)  appears,  by  the  ex- 
periments of  M.  Vauquelin,  (Ann.  de  Chim.  torn,  xlvii, 
p.  276.)  to  consist  principally  of  a  sort  of  animal  soap, 
(having  potash  for  its  basis,)  a  greasy  matter  resembling 
suet,  and  a  portion  of  lime  in  combination  with  the  car- 
bonic, acetic,  and  muriatic  acids. 

To  prepare  wool  for  dyeing,  this  yolk  is  commonly  re- 
moved, by  scowering,  or  maceration  for  a  quarter  of  an 
hour,  in  warm  water,  mixed  with  a  fourth  part  of  stale 
urine;  stirring  the  wool  frequently  by  sticks,  and  after- 
wards rincing  it  thoroughly,  if  practicable,  in  running  wa- 
ter. M.  Vauquelin,  however,  thinks  it  may  be  advantage- 
ous, after  wool  has  been  cleansed  from  every  thing  which 
clean  water  can  remove,  to  soak  it  for  a  few  hours,  not  in 
diluted  stale  urine,  but  in  a  tepid sohxXion  of  soap,  employ, 
ing  one  pound  of  the  latter,  with  a  sufficient  quantity  of 
water,  to  every  twenty  pounds  of  wool  to  be  scowered. 
M.Roard,  director  of  the  dyeing  department  of  the  French 
Imperial  manufactories,  thinks,  that  one  pound  of  Flan- 
ders soap  employed  in  this  way,  is  sufficient  for  thirty 
pounds  of  wool;  but  instead  of  a  tepid  solution  he  recom- 
mends one  that  is  heated;  though  not  above  60°  of  Reau- 
mur; equal  to  about  160°  of  Fahrenheit.*  He  also  re- 

*  M.  BerthoUet,  in  the  last  edition  of  his  Elements,  torn.  i.  p.  175, 
appears  to  think,  that  the  substitution  of  soap  for  the  ammonia  con- 


Philosophy  of  Permanent  Colows^  65 

commends  the  spinning  of  wool  in  the  yolk,  and  scowering 
it  afterwards;  when  he  says,  it  will  become  much  whiter 
than  if  scowered  before  the  spinning.  Another  advantage 
results  from  postponing  this  scowering,  which  is  that 
of  preserving  the  wool  from  the  depredations  of  moths, 
and  other  insects,  so  long  as  it  retains  the  yolk;  an  effect 
which  Reaumur  observed,  and  published  in  the  year  1738. 
(See  Mem.  de  L'Acad.  Re.  des  Sciences  for  that  year.) 
The  wool  of  healthy  sheep  is  always  more  copiously  pro- 
vided with  yolk  than  that  of  the  sickly. 

When  wool  has  been  spun  and  wove,  it  commonly 
undergoes  the  operation  o^  fulling,  which  I  shall  notice, 
because  it  depends  upon  such  2l  peculiarity  in  the  struc- 
ture of  its  fibres,  as  seems  to  increase  its  fitness  to  imbibe 
and  retain  colours  by  dyeing.  Fulling,  according  to  Sir 
William  Petty  (see  Spratt's  History  of  the  Royal  Society,) 
"  is  making  the  cloth  to  become  thicker,  with  the  dimi- 
nution of  its  other  dimensions,  and  the  covering  of  its 
threads,  so  as  that  the  cloth  shall  seem  to  be  translated  from 
the  likeness  of  a  tela,  (all  of  whose  threads  appear)  to 
that  of  a  hat,  which  has  no  threads  at  all;  for,  by  the  way, 
the  making  ©f  a  hat  (continues  he)  is  the  making  of  a  tela, 
without  spinning  or  weaving,  by  a  kind  of  fulling."  "  This 
thickening,"  he  adds,  *'  is  made  by  the  shortening  of 
threads;"  an  effect  which  he  erroneously  ascribed  to  the 
heat  of  the  mill,  and  the  supposed  astringent  operation  of 
urine,  fullers'  earth,  &c. 

tained  in  stale  urine,  has  not  been  found  advantageous  in  the  trials 
made  with  it:  M.  Chaptal,  however,  in  the  fourth  vol.  of  his  Chimie 
Appliquee  aux  Arts,  p.  423,  treating  of  this  operation,  says,  that  in 
Spain,  and  recently  in  Franoe,  cloths  have  been  scowered  without 
either  stale  urine  or  soap,  by  preserving  the  water  impregnated  with 
the  yolk,  resulting  from  one  operation,  and  employing  it  for  a  se- 
cond; and  that  of  the  second,  for  a  third,  8cc.  until  it  becomes  so 
thick,  and  overcharged  with  yolk,  as  to  be  unfit  for  use. 

Vol.  I.  I 


66  Philosophy  of  Permanent  Colours, 

M.  Monge  has,  however,  lately  given  a  better  account 
of  the  operations  of  felting  and  fulling,  (see  Ann.  de 
Chimie,  torn.  vi.  p.  300,  &c.)  by  which  it  appears,  that 
the  **  shortening  of  threads"  is  not  produced  by  heat,  or  by 
any  astringent  power  whatever,  but  an  effect  resulting 
from  the  external  conformation  of  the  fibres  of  wool,  fur, 
&c.  which  appear  to  be  formed,  either  of  small  laminae 
placed  over  each  other  in  a  slanting  direction,  fi*om  the 
root  towards  the  end  or  point  of  each  fibre,  like  the  scales 
of  fish,  lying  one  over  the  other,  in  succession,  from  the 
head  to  the  tail;  or  of  zones,  placed  one.  upon  another, 
as  in  the  horns  of  animals;  from  which  structure  each 
fibre,  if  drawn  from  its  root  towards  the  point,  will  pass 
smoothly  through  the  fingers;  but  if  it  be  drawn  in  a  con- 
trary direction,  from  the  point  towards  the  root,  a  sensible 
resistance,  and  tremulous  motion  will  be  felt  by  the  fingers. 
This  conformation  disposes  the  fibres  of  wool  to  catch 
hold  of  each  other,  and  as  they  cannot  recede,  when  acted 
upon  by  other  bodies,  they  naturally  advance,  by  a  pro- 
gressive motion,  towards,  and  beside  each  other,  from 
the  end  towards  the  root;  a  disposition  which  is  very  in- 
convenient to  spinning,  and  therefore  the  wool  is  greased, 
that  the  asperities  arising  from  this  structure  of  its  fibres 
may  be  thereby  covered,  or  sheathed,  as  a  Covering  of  oil 
sheathes  those  of  a  file.  But  the  wool  being  manufactured, 
and  the  grease  no  longer  useful,  it  is  removed  by  scow- 
ering,  not  only  for  the  sake  of  cleanliness,  but  that  it  may 
not  frustrate  the  process  of  dyeing.  The  cloth  is  therefore 
carried  to  the  fulling  mill,  and  there  subjected  to  the  action 
of  large  beetles,  with  fullers'  earth  and  water,  by  which 
the  cloth  is  not  only  scowercd,  but  its  fibres,  in  conse- 
quence of  the  structure  just  described,  being  made  to 
conjoin,  and  advance  toward,  and  beside  each  other,  be- 
come shorter,  and  more  closely  connected,  or  felted  to- 


Philosophy  of  Permanent  Colours.  67 

gether,  the  warp  and  woof  losing  in  extent,  but  gaining 
proportionably  in  thickness. 

The  laminae,  or  zones,  under  consideration,  afford  many- 
interstices  in  the  fibres  of  wool,  suited  to  receive  and  con- 
tain the  particles  of  colouring  matters,  when  applied  to 
them  in  the  operation  of  dyeing;  but  these  interstices  being 
small,  aiid  the  fibres  of  the  wool  naturally  elastic,  no  co- 
lour can  be  conveyed  into  these  cavities,  until  they  are 
dilated  by  hot  or  boiling  water;  whereas  silk,  cotton,  and 
linen,  are  made  to  receive  colours  without  heat,  as  per- 
manently as  with  it.  And  this  difference  manifestly  arises 
from  the  smallness  of  the  interstices  in  which  the  colour- 
ing particles  are  deposited  in  the  fibres  of  wool,  and  their 
elasticity;  and  as  the  colouring  particles  are  only  made  to 
enter  and  deposit  themselves  by  an  artificial  dilatation,  it 
follows  that,  when  this  ceases,  the  filaments  will  again 
contract  to  their  former  size,  upon  the  colouring  matters 
so  introduced,  and  hold  them  much  more  strongly  than 
they  are  likely  to  be  held  in  other  substances,  whose  in- 
terstices are  large  enough  to  receive  colouring  particles 
without  being  dilated,  and  which,  therefore,  cannot  be 
supposed  ever  to  contract  and  compress  them  in  the  same 
way:  and  this  difference,  joined  to  the  superior  chemical 
attraction   of  animal  fibres  for  colouring   matters,  will 
sufficiently  explain  why  many  colours  dyed  upon  wool 
prove  so  much  more  durable  than  upon  cotton  or  linen. 
Wool,  when  dyed  in  the  fleece,  takes  up  much  more  co- 
louring  matter  than  when  spun,  and  much  more  than 
when  wove  into  cloth.  It  is  also  more  or  less  penetrated, 
according  to  the  fineness  of  its  own  texture,  and  the  par- 
ticular nature  of  the  colouring  matter  with  which  it  is 
dyed:  the  very  finest  cloth  is  never  thoroughly  dyed  scar- 
let, it  being  always  found  white  within  when  cut.* 

*  The  late  Mr.  Nash,  and  his  successor,  Mr.  Pymock,  in  Glou- 
cestershire, by  causing  broad  cloths  to  be  wove  of  thi-eads  but  little 


6B  Philosophy  of  Permanent  Colours. 

Wool  taken  from  different  breeds  of  sheep,  in  vari- 
ous countries,  is  naturally  of  different  colours;  as  white, 
yellow,  reddish,  and  black.  Formerly,  all  the  flocks  in 
Spain,  excepting  those  of  Andalusia,  were  of  this  last 
colour,  it  having  been  preferred  for  wearing  by  the  Spa- 
niards; and  this  natural  (brownish)  black  is  even  at  this 
time  manufactured,  and  worn  constantly  by  some  religious 
orders  in  Roman  Catholic  countries.  The  white  wool, 
however,  is  now  almost  universally  preferred  to  every 
other,  as  being  susceptible  of  receiving  even  a  better  black 
by  dyeing,  than  any  which  is  natural.  The  cloth  worn  by 
Martialy  appears  to  have  received  none  but  the  natural 
colour  of  the  wool,  whatever  that  may  have  been.  He  says 
(xiv.  133.) 

"  Non  est  lana  mihi  mendax,  nee  mutor  aevo 
me  mea  tinxit  ovis. 

And  Virgil,  in  predicting  the  auspicious  events  which 
were  supposed  by  him  to  follow  the  birth  of  Marcellus, 
(nephew  to  Augustus),  mentions  the  sheep  as  naturally 
producing  wool,  of  the  richest  and  most  brilliant  colours. 

«  Nee  varies  diseet  mentiri  lana  colores: 
Ipse  sed  in  pratis  aries  jam  suave  rubenti 
Murice,  jam  eroeeo  mutabit  vellera  luto. 
Sponte  sua  sandyx,  pascentes  vestiet  agnos.** 

Eclogue  iv. 

The  lutum  of  the  third  of  these  lines  appears  to  have 
been  the  Reseda  luteola,  or  weld  plant,  now  used  as  a  yel- 
low dye,  and  it  has  been  conjectured  by  professor  Beck- 

twisted  in  the  spinning,  have  sueceeded  in  making  their  searlet  dye 
penetrate  farther  into  the  eloth  than  would  otherwise  have  been  prac- 
ticable; perhaps  also  this  difference  of  twisting  may  contribute  to 
the  remarkable  beauty  of  their  scarlets,  by  an  alternation  in  the  affi- 
nity of  light. 


Fhilosophy  of  Permanent  Colours.  69 

man,  that  the  sandyx  of  the  last  line,  which  is  represen- 
ted as  giving  a  red  colour  to  the  wool  of  the  lambs  feed- 
ing upon  it,  must  have  been  the  madder,  which  is  known 
to  have  grown  wild  in  many  parts  of  Italy.  Its  leaves  are 
said  to  impart  a  reddish  colour  to  the  milk  of  cows,  when 
eaten  by  them,  and  the  roots  notoriously  stain  the  bones 
of  hogs  of  a  bright  red,  when  they  make  part  of  the  food 
of  these  animals. 

Article  II.— Of  Silk. 

This  consists  of  the  fine  threads  composing  the  follicle 
of  the  Pupa,  of  the  Bombyx  Mori,  a  Moth  or  Phalena 
belonging  to  Linneus's  third  order  of  insects.  (Lepidop- 
tera.) 

It  has  been  said  and  believed,  that  silk  was  exclusively- 
produced  in  China,  until  the  reign  of  the  Greek  Emperor 
Justinian.  But  of  this  there  is  no  sufficient  evidence. 
Pliny,  indeed,  after  describing  the  countries  inhabited  by 
the  Scythians,  mentions  the  Seres  as  being  the  first  or 
nearest  civilized  people  beyond  those  regions;  and  he 
adds,  that  they  were  famous  for  the  fine  wool  combed  from 
their  trees,  of  which  he  gives  some  account,  so  indistinct, 
however,  that  we  may  doubt  whether  it  does  not  relate 
to  cotton,  rather  than  to  silk.*  But  there  is  a  passage 
much  less  equivocal  in  his  eleventh  book,  (Chap.  22,) 
where  he  mentions  a  kind  of  insects,  greater  than  the 
wasps  and  hornets  which  he  had  just  before  described, 
and  to  Vv^hich  he  gives  the  generic  name  of  Bombyx, 
adding  that  they  are  produced  in  Assyria;  and  after  a 
fabulous  account  of  the  nests  and  honey,  which  he  sup- 

*  ^'  Primi  sunt  hominum,  qui  noscantur,  Seres^  lanicio  sylvarum 
nobiles,  perfusam  aqua  depectentea  frondium  canitiem:  unde  ge- 
minus  foe  minis  nostris  labor,  redordiendi  fila,  rursumque  texendi. 
Tarn  multiplici  opere,  tarn  longinquo  orbe  petitur,  ut  in  publico 
matrona  transluceat."  Lib.  vi.  cap.  17. 


70  Philosophy  of  Permanent  Colours. 

posed  them  to  make  like  bees,  he  says,  they  engender 
in  a  diflPerent  manner;  i.  e.  from  worms  which  put  forth 
two  horns;  that  these  are  Eriiccs^  and  afterwards  change 
to  BombyUi,  then  to  NecydaU;  whence,  after  six  months, 
they  become  Bombyces,  spinning  and  weaving  webs  like 
those  of  spiders,  to  make  garments  for  luxurious  women, 
which  (garments)  are  called  Bombycina.  He  adds,  that  the 
first  who  found  means  to  unweave  these  webs,  and  weave 
them  again,  was  a  female  of  Cos^  named  Pamphila,  the 
daughter  of  Latous,  who  ought  not  to  be  defrauded  of  the 
honour  of  inventing  a  species  of  clothing,  through  which 
women  may  expose  their  beauties,  as  if  they  were  naked.* 
Though  this  account  is  manifestly  incorrect,  as  well  as 
imperfect,  there  can  be  no  doubt  of  Pliny's  intention  to 
describe  the  moth  of  the  silk  worm,  and  its  passage 
through  the  larva  and  pupa  states;  but  I  do  not  think  that 
in  his  time  the  Romans  always  distinguished  silk  from 
cotton,  as  the  terms  bombyx,  bombycina,  and  sericum, 
were  sometimes  applied  to  muslin  and  other  cotton 
cloths,  as  well  as  to  those  of  silk,  and  indeed  the  garments 
which  Pliny,  in  his  next  chapter,  mentions  as  being  made 
of  the  silk  produced  by  the  Bombyx  of  Cos^  (which  he 
represents  as  different  from  the  Assyrian^)  must  have  been 
cotton.  These^  he  says,  even  the  men  were  not  ashamed 
to  wear  in  the  summer^  when,  contrary  to  ancient  man- 
ners, they  thought  themselves  overloaded  by  any  other 
than  light  clothing.  He  adds,  however,  that  the  men  had 
not  in  his  time  begun  to  wear  the  Assyrian  silk,  but  had 

*  "  Et  alia  horum  origo  e  grandiore  vermiculo,  gemina  proten- 
dens  sui  generis  cornua:  hi  erucas  sunt:  fit  deinde,  quod  vocatur 
Bombylius:  ex  eo  Necydalus,  ex  hoc  in  sex  mensibus  Bombyx. 
Telas  araneorum  modo  texunt  ad  vestem  luxunique  foeminarum 
quae  bombycina  appellatur.  Prima  eas  redordiri,  rursusque  texere 
invenit  in  Ceo  mulier  Pamphila  Latoi  filia,  non  fraudanda  gloria  ex- 
cogitatae  rationis,  ut  denudet  foeminas  vestis.'* 


Philosophy  of  Permanent  Colours,  71 

left  it  to  adorn  females  exclusively.  '*  Nee  puduit  has 
vestes  usurpare  etiam  viros,  levitatem  propter  aestivam: 
in  tantum  a  lorica  gercnda  discessere  mores,  ut  oneri  sint 
etiam  vestes:  Assyria  tamen  bombyce  adhuc  foeminis 
cedimus.^^ 

It  seems  difficult  to  ascertain  what  nation  Pliny  intend- 
ed to  describe  under  the  name  of  Seres,  there  being  no 
proof  that  in  his  time  the  Romans  had  ever  heard  of 
China;  though  we  have  good  reason  to  believe,  that  the 
manufacture  and  use  of  silk  were  introduced  among  the 
Chinese  at  a  very  remote  period.  We  are  indeed  inform- 
ed, that  the  annals  of  China  mention  the  wife  of  an  empe- 
ror, named  Hoagti,  as  the  first  person  who  employed 
herself  in  spinning  silk,  produced  by  silk  worms  in  their 
wild  or  natural  state.  But  this  was  probably  done  as  soon 
in  other  countries,  and  especially  in  Persia,  where  both 
the  white  and  black  mulberry  trees  where  indigenous. 
Mr.  Colcbrooke  informs  us,  that  in  the  jnost  ancient 
Sanscrit  books  there  is  frequent  mention,  not  only  of 
silk,  but  of  an  Indian  class,  whose  occupation  was  to  attend 
silk  worms.  See  Asiatic  Researches,  vol.  v. 
*  It  is  indeed  probable,  that  the  very  small  portion  of 
silk  which  had  found  its  way  to  Rome,  in  or  before 
Pliny's  time,  came  not  from  China,  but  Persia;  whence 
the  Greeks,  who  returned  from  the  army  of  Alexander 
the  Great,  appear  to  have  first  brought  wrought  silk  into 
Greece,  about  223  years  before  the  Christian  iEra:  and 
the  emperor  Heliogabalus  is  said  to  have  been  the  first 
person  who,  about  440  years  afterwards,  wore  a  Holose- 
ricum,  or  garment  composed  entirely  of  silk,  which  com- 
modity was  then  rarely  sold  for  less  than  its  weight  in 
gold;  and  it  is  related,  I  think,  by  Nopiscus,  that  the  em- 
peror Aurelian  resisted  the  earnest  solicitations  of  his 
empress,  for  a  robe  of  silk,  as  being  too  costly. 

But  about  the  year  550,  two  monks  brought  from 


72  Philosophy  of  Permanent  Colours, 

India  to  Constantinople  a  quantity  of  the  eggs  of  the 
bombyx  mori,  which  they  had  carefully  deposited  in  hol- 
low canes;  and  the  eggs  being  hatched  by  the  warmth  of 
a  dunghill,  and  the  larvae  fed  on  the  leaves  of  wild  mul- 
berry trees,  the  insects,  under  the  protection  of  the  em- 
peror Justinian,  were  rapidly  multiplied  in  the  Pelopon- 
nesus, and  other  parts  of  Greece;*  whence  they  were 
afterwards  carried  to  Sicily,  and  several  parts  of  Italy. 
In  the  13th  century,  the  Venetians  established  very  ex- 
tensive manufactories  of  silk,  in  their  territories,  as  did 
the  Florentines  in  the  next  century.  Afterwards,  the 
Moors  introduced  silk  worms,  and  the  manufacture  of 
silk,  into  the  southern  parts  of  Spain,  particularly  Murcia, 
Grenada,  and  Cordova,  whence  silk  stockings  were 
brought  over  to  our  Henry  the  8th,  and  Edward  the  6th. 
Henry  the  2d  of  France,  is  said  to  have  been  the  first 
person,  who  wore  silk  stockings  in  that  kingdom,  (at  the 
marriage  of  his  daughter,  and  that  of  his  sister;)  and  we 
are  told,  that  a  pair  of  black  silk  stockings,  having  been 
presented  to  Queen  Elizabeth,  she  was  highly  pleased 
with  them,  and  resolved  never  afterwards  to  wear  any 
other  than  silk  stockings. 

Though  the  silk  of  the  Bombyx  mori,  greatly  excels 
that  of  other  moths,  by  its  abundance,  pliability,  and  bril- 
liancy, as  well  as  the  facility  with  which  it  may  be  reeled, 
it  is  not  the  only  production  of  this  kind,  capable  of  be- 
ing made  useful  to  mankind. 

The  Phalena  Atlas  Lin.  produces  in  China  very  large 
cocoons,  and  their  silk  is  remarkably  strong,  but  being 
difficult  to  reel  it  is  commonly  spun. 

The  Phalena  Cynthia,  (or  Arrindy  silk  worm,)  also,  is 
a  beautiful  moth,  of  which  the  natives  of  the  interior, 
north-eastern  part  of  Bengal,  breed  great  numbers,  as 

*  See  Procopius,  lib.  iv.  cap.  17,  de  Bello  Gothico. 


philosophy  of  Permanent  Colours.  73 

they  do  of  the  common  silk  worm,  in  a  domestic  state.  Its 
caterpillar  is  very  large,  and  feeds  voraciously  on  the 
leaves  of  the  common  Ricinus,  or  Palma  Christi.  The  co- 
coons of  this  moth,  according  to  Dr.  Roxburgh,  '*  are  re- 
markably soft  and  white,  or  yellowish,  but  the  filaments  are 
so  exceedingly  delicate,  as  to  render  it  impractible  to  wind 
off  the  silk:  it  is  therefore  spun  like  cotton.  The  }  arn  thus 
manufactured,  is  wove  into  a  coarse  kind  of  white  cloth,  of 
a  seemingly  loose  texture,  but  of  incredible  durability;  die 
life  of  one  person,  being  seldom  sufficient  to  wear  out  a 
garment  of  it;  so  that  the  same  piece  descends  from  mo- 
ther to  daughter."  It  must,  however,  be  washed  only  in 
cold  water,  for  if  put  into  that  which  is  boiling,  it  will 
"tear  like  old  rotten  cloth." 

Dr.  Roxburgh  also  describes  another  silk  worm,  the 
Tussach,  or  Phalena  Paphia,  which  is  "  found  in  such 
abundance  over  mawy  parts  of  Bengal,  and  the  adjoining 
provinces,  as  to  have  aflforded  to  the  natives,  from  time 
immemorial,  an  abundant  supply  of  a  most  durable  codivs^ 
dark-coloured  silk,  commonly  called  Tussach  silk,  which 
is  woven  into  a  kind  of  cloth,  called  Tussach  doot'hies, 
much  worn  by  Bramins  and  other  sects  in  India."  This 
cloth,  as  the  doctor  thinks,  might  *'  be  highly  useful  to 
the  inhabitants  of  many  parts  of  America,  and  the  south 
of  Europe,  where  a  cheap,  light,  cool,  durable  dress,  such 
as  this  silk  makes,  is  much  wanted."  See  the  Transactions 
of  the  Linnasan  society,  Vol.  — ,  p.  33,  &c. 

Silk  is  naturally  covered  with  a  kind  of  varnish,  or 
gummy  substance;  and  almost  the  whole  of  that  known 
in  Europe,  is  moreover  tinged  of  a  yellow  colour,  which, 
for  most  purposes,  it  is  necessary  to  remove,  as  well  as 
the  varnish.  This  is  commonly  done  by  submitting  it  to 
the  action  of  soap,  in  circumstances  which  M.  Berthollet 
has  described,  as  well  as  some  other  means  for  answering 
this  double  purpose.  (Tom.  i.  p.  184,  &c.) 

Vol.  I.  K 


74  Philosophy  of  Permanent  Colours, 

M.  Roard,  (director  of  the  Imperial  French  dyes,  at  the 
Gobelins)  has  lately  ascertained,  that  besides  the  gummy 
and  colouring  matters,  there  is  a  substance,  much  like 
wax,  to  be  removed  in  this  operation,  (decreusage. )  He 
states  the  gummy  matter,  as  commonly  amounting  to 
twenty-three  or  twenty-four  per  cent,  of  the  silk,  and  to 
be  soluble  in  water:  and  the  colouring  matter  to  make 
about  a  55th,  or  60th  part  of  the  silk.  It  is  very  soluble 
in  alcohol,  but  not  in  water.  The  wax  seldom  exceeds  the 
hundreth  part  of  the  silk,  and  is  often  not  more  than  half 
so  much.  All  these  matters  may,  he  thinks,  be  removed 
with  better  effect,  by  soap  than  by  soda:  and  as  silk  by 
long  boiling,  after  it  has  been  made  white,  often  becomes 
yellow  again,  and  is  moreover  hurt  in  its  texture,  M. 
Roard  thinks,  that  instead  of  employing  the  so2ip  partially, 
or  at  different  times,  as  has  been  frequently  practised,  it 
is  best  at  once  to  employ  the  whole  quantity  likely  to  be 
wanted,  and  thereby  shorten  the  time  of  boiling  to  an 
hour,  or  an  hour  and  one  half;  which  will  commonly  suffice, 
and  leave  the  silk  with  more  of  its  natural  lustre,  and  greater 
softness,  as  well  as  strength.  M.  Roard,  indeed,  thinks,  that 
when  silk  is  to  be  dyed  of  a  crimson,  or  any  other  colour, 
to  which  its  natural  yellow  would  not  prove  unsuitable,  it 
is  best  not  to  remove  the  latter  completely,  because,  when 
this  is  done,  the  dyed  colour  is  commonly  found  to  have 
less  brilliancy,  than  it  would  otherwise  have  had. 

When  silk  has  been  freed  from  both  its  gummy  var- 
nish, and  its  yellow  colour,  it  is  sometimes  necessary  to 
whiten  it  still  farther,  by  the  fumes  of  sulphur  applied  to 
it,  and  confined  in  a  stove.  But  though  sulphureous  acid 
gas,  applied  in  this  way,  readily  v^^hitens  the  silk,  and 
thereby  renders  it  more  fit  to  exhibit  lively  colours,  a  por- 
tion of  sulphur  adheres  to  it,  which,  when  it  is  intended 
to  be  dyed,  must  be  removed  by  soaking  and  agitation, 
for  a  considerable  time,  in  warm  water,  that  it  may  not 


Philosophy  of  Permanent  Colours,  75 

tarnish  the  colours;  an  effect  which  sulphur  generally  pro- 
duces, to  those  of  wool  and  silk.  The  lustre  so  much  de- 
sired, in  colours  dyed  upon  silk,  seems,  in  a  great  degree, 
to  depend  upon  its  smooth  glossy  surface,  which  acids, 
alkalies,  and  other  chemical  agents  (particularly  the  solu- 
tions or  oxides  of  tin,)  contribute  to  impair,  and  are  there- 
fore to  be  sparingly  used* 

Silk,  in  its  disposition  to  receive,  and  retain  colours  for 
dyeing,  seems  to  partake  of  a  middle  nature,  between  that 
of  the  animal  and  vegetable  substances:  by  its  abundance 
of  nitrogcne,  and  hydrogene,  it  possesses,  like  wool,  a 
strong  attraction  for  colouring  matters;  but  its  fibres 
having  neither  a  similar  organization,  nor  an  equal  degree 
of  elasticity,  it  is  capable  of  imbibing  colours,  like  linen 
and  cotton,  without  any  previous  dilatation  of  its  pores  by 
hot  water,  but,  like  them,  it  parts  with  colours,  so  im- 
bibed, the  more  easily,  in  consequence  of  this  natural 
openness,  or  the  want  of  contraction,  in  its  pores;  though, 
upon  the  whole,  colours  dyed  in  silk  are  more  lasting,  than 
when  dyed  in  linen  and  cotton,  on  account  of  its  greater 
affinity  with  colouring  matters,  which  seems  to  result  from 
its  animal  nature. 

In  the  year  1709,  Mr.  Bon,  First  President  of  the 
Chambre  des  Comptes,  aides,  et  finances,  at  Montpellier, 
communicated  to  the  Royal  Society  of  that  city,  a  disco- 
very which  he  had  made  of  a  new  kind  of  silk,  from  the 
very  fine  threads,  with  which  several  species  of  spiders 
entwine  their  eggs;  which  threads  were  found  to  be  much 
stronger  than  those  composing  the  spider's  web.  They 
were  easily  separated,  carded,  and  spun,  and  then  afforded 
a  much  finer  and  stronger  thread  than  that  of  the  com- 
mon  silk,  though  somewhat  less  glossy.  They  were  also 
found  capable  of  receiving  all  the  different  dyes,  with  equal 
facility.  Three  ounces  of  this  new  silk,  made  a  pair  of  du- 
rable stockings  of  the  largest  size;  and  as  the  spiders  were 


76  Philosophy  of  Permanent  Colours. 

much  more  prolific,  and  much  more  hardy  than  the  silk 
worms,  great  expectations  were  formed,  of  benefit  from 
this  discovery.  M.  Reaumur,  therefore,  took  up,  and  pro- 
secuted the  inquiry  with  zeal.  He  conceived  that,  when 
spiders  were  artificially  multiplied  for  the  production  of 
silk,  it  would  be  impossible  to  provide  them  sufficiently 
with  flies,  their  natural  food.  This  obstacle,  however,  was 
soon  removed,  by  his  finding  that  they  would  subsist  very 
well,  upon  earth  worms  chopped,  and  upon  the  soft  ends 
or  roots  of  feathers.  But  a  new  obstacle  arose  from  their 
unsocial  propensities,  which  proved  insurmountable;  for 
though  at  first  they  seemed  to  feed  quietly,  and  even  work 
together,  several  of  them  at  the  same  web,  yet  they  soon 
began  to  quarrel,  and  the  strongest  devoured  the  weakest, 
so  tUat  of  two  or  three  hundred,  placed  together  in  a  box, 
but  three  or  four  remained  alive  after  a  few  days;  and  no- 
body could  propose  to  keep  and  feed  each  separately. 
M.  Reaumur  found  ^heir  silk  to  be  naturally  of  different 
colours;  particularly  white,  yellow,  sky  blue,  grey,  and 
coffee -coloured  brown.  See  Hist,  et  Mem.  de  PAcad. 
Roy  ale  des  Sciences,  ann.  1710.  See  also  a  Dissertation 
by  M.  Bon,  "sur  I'utilite  de  la  soye  des  Arraignees."  8vo. 

Article  III. — Of  Cotton. 
This  is  the  well  known  production  of  a  genus  of  plants, 
denominated  Gossypium;  of  which  Linneus  has  described 
five  species,  viz.  G.  herbaceum,  G.  arboreum,  G.  hirsu- 
turn,  G.  religiosum,  and  G.  Barbadense.  To  these,  five 
other  species  have  been  added,  partly  indeed  by  elevating 
to  the  rank  of  distinct  species,  several  which  had  pre- 
viously been  considered  as  merely  varieties  of  some  of  the 
former.  This  addition  consists  of  G.  Indicum,  G.  mi- 
Cranthum,  G.  vitifohum,  G.  latifolium,'  and  G.  peruvia- 
num.  But  as  the  specific  characters  of  these  several  species 
are  not  connected  with  the  subject  of  dyeing,  or  calico 


Philosophy  of  Permanent  Colours*  77 

printing,  a  particular  account  of  them  would  be  here  su- 
perfluous. The  fibres  of  cotton  differ  not  only  in  their 
length,  fineness,  and  strength,  but  also  in  their  colours. 

Most  of  the  species  of  Gossipium,  produce  cotton 
which  is  naturally  white,  though  a  few  produce  it  of  other 
colours,  of  which  that  called  Nankin  by  the  English,  and 
**coton  a  couleur  rousse  (de  Siam),"  by  the  French,  is 
best  known.  Von  Rohr,  who  was  employed  by  the  Da- 
nish government  as  a  botanist,  during  ten  years,  in  the 
West  Indies,  has  described  three  species  of  this  Nankin 
cotton,*  which  he  distinguishes  chiefly  by  peculiarities  in 
their  respective  seeds. 

Cotton  of  this  colour  has  been  long  cultivated  in  China, 
and  more  especially  along  the  sea  shores  of  the  south- 
eastern part  of  the  province  of  Kiang-nam,  of  which  Nan- 
kin is  the  capital,  as  it  formerly  was  of  the  Chinese  em- 
pire. It  is  also  now  cultivated  at  Malta,  and  in  some  of  the 
West  India  islands,  and  is  said  to  grow  naturally  in  Africa. 
It  is  asserted,  that  a  species  of  cotton,  naturally  of  a  bright 
yellow  colour,  is  produced  in  Dahomy^  but  that  the  ex- 
portation of  it  is  prohibited,  by  the  government  of  that 
part  of  Africa.  Mr.  Clarkson  has  mentioned  a  species  of 
cotton,  naturally  of  a  crimson  colour,  as  also  growing  in 
Africa,  particularly  in  the  Eyeo  country;  of  which  a  small 
specimen  was  brought  to  Great  Britain  in  the  year  1796. 
He  adds,  that  "  the  value  of  this  cotton  would  be  great, 
both  to  the  importer  and  to  the  manufacturer  of  muslins;" 
that  *'  the  former  would  immediately  receive  eight  shil- 
lings the  pound  for  it,  and  the  latter  would  gain  conside- 
rably more  by  his  ingenuity  and  taste." 

Lieutenant  Matthews  also,  in  describing  the  several 

*  See  "  Anmerkungen  ueber  den  Cattunbau,  zum  nuzon  der 
Daenischen  Westindischen  Colonien,  Sec.  von  J.  P.  B.  Von  Rohr." 
Altona,  1793.  2  vols.  12mo. 


78  Philosophy  of  Permanent  Colours. 

species  of  cotton  produced  at  Sierra  Leone,  mentions  one, 
of  a  pale  red  or  pink  colour:  and  the  late  Mr.  Bryan  Ed- 
wards, in  his  History  of  the  West  Indies,  (vol.  iii.  p.  199, 
8vo.)  mentions,  as  growing  M^ild  in  the  Spanish  part  of 
St.  Domingo,  "  a  species  of  cotton  of  which  the  wool  is 
reddish,''^ 

Cotton  offers  to  the  industry  and  wants  of  mankind  a 
filaceous  substance,  which,  without  the  tedious  artificial 
preparation  required  for  hemp  and  flax,  has,  during  many 
ages,  especially  in  warm  climates,  constituted  the  most 
useful,  as  well  as  ornamental  and  graceful  parts  of  their 
clothing.  Whatever  obscurity  or  uncertainty  there  may 
be  in  some  parts  of  Pliny's  History,  relating  either  to  silk 
or  cotton,  there  is  but  little  of  either,  in  his  account  of 
the  cotton  of  Upper  Egypt,*  growing  on  a  shrub,  which 
some  (says  he)  call  Gossipium,  other  Xylon,  and  the  cloth 
made  of  its  wool,  Xylina.  It  is  but  small,  and  produces  a 
fruit  resembling  the  bearded  nut,  (filberd)  from  whose 
interior  capsule,  a  fine  wool  is  spun,  which  no  linen  can 
excel  in  softness  and  whiteness.  Of  this,  he  adds,  are  made 
those  sacerdotal  garments,  in  which  the  priests  of  Egypt 
greatly  delight. 

Vossius  thinks  Gossipion,  or  Gossypium,  to  have  been 
an  Egyptian  word;  the  Greek  name  of  cotton  (Xylon)  was 
abbreviated  from  Eryxylon,  which  signified  tree  wool; 
and  the  German,  Dutch,  Swedish,  and  Danish  names  of 
cotton,  have  this  signification.  The  Arabian  name  is  co» 
turn;  and  the  English  and  French,  probably,  became  ac- 
quainted with  it,  by  joining  in  what  were  called  the  Holy 

*  Superior  pars  iflgypti  in  Arabian!  vergens,  gignit  fruticem, 
quern  aliqui  Gossipion  vocant,  plures  Xylon,  et  ideo  Una  inde  facta 
Xylina.  Parvus  est,  similemque  barbatae  nucis  defert  fructum,  cujus 
ex  interiore  bombyce  lanugo  netur:  nee  Una  sunt  ei  candore  mol- 
Utiave  preferenda.  Vestes  inde  Sacerdotibus  iEgypti  gratissimae." 
Lib.  xix.  cap.  i. 


Philosophy  of  Permanent  Colours.  79 

wars,  and  changed  it  to  cotton^  and  coton.  The  Italians  also 
borrowed  their  name  of  cotone  from  the  Arabs,  and  their 
other  name  of  bombagia,  from  that  of  bombax,  one  of  the 
names,  by  which  the  Latins  designated  the  wool-bearing 
trees,  ^''  arbor es  lanigene'^''  of  Pliny,  who,  in  his  twelfth 
book,  chapter  3,  notices  a  secondtiVHQ^  these  ivool-bearing 
trees  in  the  country  of  the  Seres;  but  so  ambiguously, 
that  I  cannot  help  wondering,  how  it  should  have  been  so 
generally  believed,  that  the  Seres  were  Chinese,  and  that 
silk,  rather  than  cotton,  was  in  Pliny's  contemplation, 
when  he  mentioned  the  wool  of  their  trees.*  The  impor- 
tant benefits  derived  to  mankind  from  the  different  spe- 
cies of  cotton  shrubs,  have  caused  them  to  be  cultivated 
more  extensively  perhaps  than  any  other  vegetable.  In 
China,  it  is  planted  from  Canton  to  Pekin,  and  from  the 
western  shores  of  that  empire,  to  the  deserts  adjoining  to 
Hindostan;  and  also  along  the  coasts  of  the  two  Indian 
Peninsulas,  with  those  of  Arabia,  and  throughout  the 
Mogul  empire,  and  the  innumerable  islands,  of  the  Indian 
ocean.  It  appears  to  have  been  known  from  the  remotest 
times,  of  which  we  have  any  account,  in  Persia,  Hindos- 
tan, Egypt,  and  ^Ethiopia;!  and  was  found,  also,  by  Co- 
lumbus, and  succeeding  adventurers  to  America,  in  all 

*  Mr.  Barrow,  in  a  note  to  p.  436,  of  his  travels  in  China,  makes 
the  following  observation,  "  Ptolomy  the  geographer,  places  Serica, 
adjoining  to  Scythia  extra  Imaum^  corresponding  with  Cashgar, 
Tangut,and  Kitai,  countries  famous  for  the  cultivation  of  the  cotton 
plant.  It  would  seem,  indeed,  from  all  the  passages  which  occur  in 
ancient  authors,  concerning  the  Seres^  that  cotton  was  the  substance 
alluded  to,  rather  than  silk,  and  that  these  people  were  not  the  pre- 
sent Chinese,  but  the  Tartars  of  Kitai." 

t  Herodotus,  Lib.  iii.  106,  when  writing  of  India,  mentions  trees 
growing  wild,  and  instead  of  fruit,  bearing  a  sort  of  wool,  finer  and 
better  than  that  of  sheep;  and  he  adds,  that  the  Indians  clothed 
themselves  with  wool  gathered  from  these  trees.  Arrian,  also,  on 


80  Fhilosophy  of  Permanent  Colours, 

the  intertropical  coasts  and  islands  on  that  continent.  Its 
introduction  to  Greece,  Malta,  Sicily,  Apulia,  and  Spain, 
was  probably  effected  by  the  Saracens. 

Such  quotations  might  be  multiplied,  but  I  have  given 
more  than  enough  of  them. 

The  structure  of  the  fibres  of  cotton  has  not  been  u^ell 
ascertained.  Lewenhoeck,  by  microscopical  examinations, 
found  each  of  them  to  have  two  sharp  sides;  and  it  seems 
to  be  owing  to  this  circumstance,  or  to  their  possessing 
some  asperities  like  the  filaments  of  wool,  that  cotton 
greatly  irritates  and  inflames  wounds,  ulcers,  &c.  if  appli- 
ed to  them  instead  of  lint,  from  which  they  differ  totally 
in  this  respect;  and  perhaps  the  particular  structure  which 
occasions  this  difference,  also  occasions  some  in  the  con- 
formation and  number  of  their  pores,  to  which  we  may 
probably  ascribe  the  disposition  which  cotton  manifests, 
to  admit  and  retain  colours  better  than  linen,  though  not 
so  well  as  wool  and  silk,  because  its  vegetable  nature  does 
not  afford  it  equal  attraction  for  colouring  matters. 

M.  Ic  Pileur  d'Apligny  endeavoured  to  explain  the 
cause,  why  colours  are  less  durable  when  dyed  in  silk, 
cotton,  and  linen,  that  in  wool,  by  supposing  that  the 
pores  of  the  three  first  of  these  substances,  were  smaller 
than  those  of  wool;  and  that  therefore  colouring  particles 
could  not  enter  into  them  so  easily  and  freely  as  into 
those  of  wool.  But  the  very  reverse  of  this  supposition 
seems  true,  there  being  little  difficulty  in  making  silk, 
cotton,  or  linen,  imbibe  colours,  even  when  topically  ap- 
plied cold,  without  any  artificial  dilatation  of  their  pores, 
which  is  necessary  in  the  dyeing  of  wool.  The  real  diffi- 

the  authority*  of  Nearchus,  says,  the  Indians  clothe  themselves  with 
linen  produced  upon  trees:  and  Virgil  mentions  the 

"  Nemora  ^thiopum  molli  canentia  lana." 

Georg.  ii.  V.  120. 


Philosophy  of  Permanent  Colours.  81 

culty,  therefore,  is  not  in  making  them  imbibe,  but  in 
making  them  retain,  the  colouring  particles  when  imbi- 
bed; because,  being  admitted  so  readily,  into  their  undi- 
lated  pores,  they  cannot  be  afterwards  compressed,  and 
held  therein,  by  any  contraction  of  these  pores,  as  is  done 
in  those  of  wool.  We  know  that  it  requires  twice  as  much 
cochineal,  to  produce  a  crimson  on  silk,  as  on  wool;  which 
is  a  proof  that  it  can  take  up  a  greater  quantity,  and  con- 
sequently that  its  pores  are  at  least  sufficiently  large,  and  ac- 
cessible: we  know  also,  that  unbleached  cotton  is  always  pre- 
ferred for  dyeing  the  Turkey  red,  it  being  found  to  retain 
the  colour  most  permanently;  doubtless,  because  its  pores, 
or  interstices  are  less  open  before,  than  after  the  operation  of 
bleaching.  This  is  also  the  case  of  raw  or  unsecured  silk, 
which,  as  the  ingenious  Mr.  Henry  of  Manchester,  ob- 
serves, is  "  more  easily  and  permanently  dyed,  than  that 
which  has  passed  the  above  described  process,"  of  whiten- 
ing and  scouring:  and,  indeed,  the  openness  of  the  pores 
of  cotton  and  linen,  and  their  consequent  readiness  to  im- 
bibe, both  colouring  particles,  and  the  earthy  or  metallic 
bases  employed  to  fix  most  of  them,  are  circumstances 
upon  which  the  art  of  calico  printing  is  in  a  great  degree 
founded.    To  prepare  and  dispose  cotton  for  receiving 
colours  by  dyeing,  it  is  commonly  boiled,  in  a  very  diluted 
solution  of  vegetable  or  fossil  alkali,  for  about  two  hours, 
and  afterwards  rinced  in  clean  running  water;  and  for  cali- 
co printing,  it  is  soaked  in  water,  acidulated  with  about 
one-fiftieth  of  its  weight  of  sulphuric  acid,  and  afterwards 
rinced  thoroughly  in  a  clear  stream  of  water.  Cotton  bears 
the  action  of  acids  much  better  than  either  wool  or  linen. 

Concerning  flax,  and  its  conversion  to  linen,  so  much 
has  been  written,  both  by  ancient  and  modern  authors,  and 
its  preparation  for  dyeing  so  nearly  resembles  that  of  cot- 
ton, that  I  may  hope  to  be  excused,  for  not  discussing  this 
subject. 

Vol.  I.  L 


82  Philosophy  of  Permanent  Colours. 


CHAPTER  III. 

Of  the  different  Kinds  and  Properties  of  colouring  Mat- 
ter, employed  in  Dyeing,  Calico  Printing,  ^c, 

**  Toutes  les  choses  visibles  se  distinguent  ou  se  rendent  desirable  par  la  couleur.'* 
Colbeht.  Instruction  general potir  la  Teinture,  &c. 

By  colouring  matter,  I  understand  a  substance  which 
possesses,  or  acquires  a  power  of  acting  upon  the  rays  of 
light,  so  as  either  to  absorb  them  all,  and  produce  the 
sensation  of  black;  or  only  to  absorb  particular  rays,  and 
transmit  or  reflect  others,  and  thereby  produce  the  percept 
tion  of  that  particular  colour,  which  belongs  to  the  ray  or 
rays  so  transmitted  or  reflected. 

Among  minerals,  the  colouring  matter  of  each  is  com- 
monly distributed  equally  to  all  its  parts;  but  in  animal 
and  vegetable  substances,  it  generally  exists  in  particular 
parts,  or  particles,  which  are  capable  of  being  extracted 
and  collected  for  the  purposes  of  dyeing,  &c. 

Colouring  matters  possess  peculiar  chemical  properties, 
which  distinguish  them  from  all  other  kinds  of  matter;  for 
besides  their  several  affinities  with  particular  rays  of  light, 
they  have  others  which  render  them  susceptible  of  being 
acted  upon,  and  modified  by  a  variety  of  chemical  agents, 
as  well  as  of  forming  permanent  combinations  with  the 
filaments  of  wool,  silk,  cotton,  linen,  Sec.  But  in  respect 
of  these  affinities,  colouring  matters  also  differ  essentially 
from  each  other,  and  must  therefore  be  applied  in  differ- 
ent ways,  and  with  very  different  means,  to  produce  per- 
manent colours  in  other  matters.  The  art  of  dyeing  is 
founded  upon  a  knowledge  of  the  particular  properties 
and  afliinities  of  these  matters,  not  only  as  far  as  they  relate 
to  the  substances  intended  to  be  dyed,  but  also  as  far  as 
they  are  connected  with  the  operations  of  other  agents,  by 


Philosophy  of  Permanent  Colours.  83 

which  they  are  liable  to  be  acted  upon,  either  during  the 
process  of  dyeing,  or  afterwards. 

Many  species  of  animal  and  vegetable  colouring  mat- 
ters, suffer  nearly  similar  changes  from  the  action  of  acids, 
alkalies,  and  other  chemical  agents;  from  which  it  may 
be  presumed,  that  there  is  something  of  a  common,  or 
similar  nature,  in  the  constitution  of  many  of  them.  But 
though  it  would  be  highly  useful  to  establish  general 
principles  and  conclusions  on  this  subject,  we  are  not  yet 
furnished  with  the  necessary  facts;  and  whilst  this  con- 
tinues to  be  the  case,  it  will  be  best  to  wait,  or  rather 
seek,  for  more  knowledge,  and  avoid  fallacious  supposi- 
tions or  explanations. 

Sir  Isaac  Newton  supposed  eoloured  matters  to  reflect 
the  rays  of  light;  some  bodies  reflecting  the  more,  others 
tlie  less  refrangible  rays  most  copiously;  and  this  he  con- 
ceived to  be  the  true,  and  the  only  reason  of  their  colours. 
Mr.  Delaval,  however,  has  lately  maintained  (in  the  2d 
vol.  of  the  memoirs  of  the  Philosophical  and  Literary  So- 
ciety of  Manchester,)  "  that,  in  transparent  coloured  sub- 
stances, the  colouring  matter  does  not  reflect  any  light; 
and  that  when,  by  intercepting  the  light  which  was  trans- 
mitted, it  is  hindered  from  passing  dirough  substances, 
they  do  not  vary  from  their  former  colour  to  any  other 
colour,  but  become  entirely  black:"  and  he  instances  a 
considerable  number  of  coloured  liquors,  none  of  them 
endued  with  reflective  powers,  which,  when  seen  by  tranS' 
mitted  light,  appeared  severally  in  their  true  colours;  but 
all  of  them,  when  seen  by  incident  light,  appeared 
black:  which  is  also  the  case  of  black  cherries,  black  cur- 
rants, and  blackberries,  &c.,  the  juices  of  which  appear 
red  when  spread  on  a  white  ground,  or  otherwise  viewed 
by  transmitted,  instead  of  incident  light;  and  he  con- 
cludes, that  bleached  Unen,  cotton,  &c.  *'  when  dyed 
or  painted  with  vegetable  colours,  do  not  differ  in  their 


84  Philosophy  of  Permanent  Colours, 

manner  of  acting  on  the  rays  of  light,  from  natural  vege- 
table bodies;  both  yielding  their  colours  by  transmit- 
ting through  the  transparent  coloured  matter,  the  light 
which  is  reflected  from  the  white  ground:"  it  being  ap- 
parent, from  different  experiments,  *'  that  no  reflective 
power  resides  in  any  of  their  component  parts,  except  in 
their  white  matter  only,"  and  that  '*  transparent  coloured 
substances,  placed  in  situations  by  which  the  transmission 
of  light  through  them  is  intercepted,  exhibit  no  colour, 
but  become  entirely  black." 

"  The  art  of  dyeing,  therefore,  (according  to  Mr.  De- 
laval,)  consists  principally  in  covering  white  substances, 
from  which  light  is  strongly  reflected,  with  transparent 
coloured  media,  which,  according  to  their  several  co- 
lours, transmit  more  or  less  copiously  the  several  rays 
reflected  from  the  white  substances,"  since  "  the  trans- 
parent media  themselves  reflect  no  light;  and  it  is  evi- 
dent that  if  they  yielded  their  colours  by  reflecting, 
instead  of  transmitting  the  rays,  the  whiteness,  or  co- 
lour of  the  ground  on  which  they  are  applied,  would 
not  in  any  wise  alter  or  affect  the  colours  which  they 
exhibit." 

Having  had  reason  to  differ  from  Mr.  Delaval  on 
other  points,  I  am  happy  in  being  able  to  agree  with 
him  on  this,  so  far  as  relates  to  transparent  colouring 
matters,  when  applied  to  wool,  silk,  &c.  without  the 
interposition  of  any  earthy  or  metallic  basis.  But  when 
any  such  opake  basis  is  interposed,  the  reflection  is, 
doubtless,  made  principally  by  it,  rather  than  by  the 
substance  of  the  dyed  wool,  silk,  &c.,  and  more  espe- 
cially when  such  basis  consists  of  the  white  earth  of 
alum,  or  the  white  oxide  of  tin;  which,  by  their  strong 
reflective  powers,  greatly  augment  the  lustre  of  colours. 
There  are,  moreover,  some  opake  colouring  matters, 
particularly  the  acetous,  and  other  solutions  of  iron, 


Philosophy  of  Permanent  Colours.  85 

used  to  stain  linen,  cotton,  &c.,  which  must  necessarily 
themselves  reflect,  instead  of  transmitting  the  light  by 
jvhich  their  colours  are  made  perceptible. 

It  has  been  already  mentioned,  that  when  the  rays  of 
light  are  separated  from  each  other  by  the  prism,  in 
consequence  of  their  different  degrees  of  refrangibility, 
they  produce  a  perception  of  seven  distinct  colours, 
with  all  their  intermediate  shades;  and  that  these  are  all 
equally  simple  and  primitive.  There  is,  however,  this 
peculiar  property  belonging  to  the  red,  yellow,  and  blue 
colours,  whether  prismatic  or  permanent,  ihat  they  are 
incapable  of  being  produced,  like  all  the  rest,  by  the 
combination  of  any  other  colours.  Blue  and  red  will 
compose  a  purple;  blue  and  yellow,  a  green;  red  and 
yellow,  an  orange,  &c.;  but  none  of  these,  by  any  com- 
position, will  produce  either  the  blue,  yellow,  or  red: 
these  last,  therefore,  are  in  all  cases  simple  or  uncom- 
pounded;*  but  all  the  others  may  be,  and  in  reality  are, 
sometimes  simple,  and  sometimes  compounded;  and 
this  is  true  not  only  of  those  which  are  merely  prisma- 
tic colours,  but  of  those  which  exist  naturally  in  bodies, 
or  are  communicated  by  painting,  dyeing,  &c.  Iron,  as 
has  been  already  mentioned,  will,  by  different  degrees 
of  oxydation,  produce  all  possible  varieties  of  colour; 
and  these  colours  will  be  all  simple,  or  uncompounded; 
and  so  will  the  purple  of  gold,  the  green  of  copper,  and 
the  other  colours  found  in  the  several  oxides  of  metals. 
This  is  also  the  case  of  the  violet  and  purple  dyed  from 
logwood;  of  the  green  of  the  leaves,  &c.  of  vegetables; 

*  Dufay  would  only  admit  of  three  primitive  colours,  red,  blue, 
and  yellow,  because  with  these  dyers  and  painters  can  readily 
compound  all  the  others;  and  a  late  writer,  adopting  Dufay *s  opi- 
nion on  this  subject,  says,  the  colours  of  the  prism  are  immaterial, 
accidental,  and  artificial.  But  those  of  the  dyer  and  painter  are 
substantial,  natural,  and  palpable. 


86  Philosophy  of  Permanent  Colours, 

and  of  the  orange  dyed  from  the  quercitron  bark,  as 
will  be  hereafter  mentioned.  And  among  animal  co- 
lours, numerous  instances  may  be  alleged  of  simple  or 
uncompounded  greens,  oranges,  purples,  and  violets: 
even  the  yellowish  white  liquor  of  the  murex,  and  buc- 
cinum,  from  which  the  celebrated  Tyrian  purple  was 
produced,  passes  quickly  through  all  the  shades  of  yel- 
low, green,  violet,  and  purple,  upon  being  exposed  to 
the  sun;  and  these  must  necessarily  be  deemed  simple, 
not  compound  colours.  But  on  the  other  hand,  dyers, 
painters,  &c.  daily  produce  orange,  green,  purple,  and 
violet,  by  mixtures  of  the  blue,  yellow,  and  red:  nor  is 
it  necessary  that  these  should  be  intimately  mixed, 
since  cloth  woven  from  a  red  warp,  and  a  blue  woof, 
will  appear  to  be  uniformly  purple  or  violet;  or  if  the 
warp  be  yellow  instead  of  red,  the  cloth  will  appear 
green^  in  each  case  exactly  resembling  the  simple  ho- 
mogeneous colour,  which,  in  the  prismatic  series,  lies 
between  the  colours  of  the  warp  and  woof.  It  has  more- 
over been  repeatedly  found  in  dyeing  compound  co- 
lours, as  for  instance,  green,  that  laying  a  permanent 
blue  over  a  fugitive  yellow,  does  not  defend  the  latter, 
or  make  it  in  any  degree  more  lasting,  but  that  it  will 
decay  (leaving  the  blue  in  full  strength)  as  rapidly  as 
if  no  blue  had  been  applied;  and  therefore  we  may  pre- 
sume, that  the  fibres  of  the  dyed  stuflf  were  but  partly 
covered  with  the  yellow  colouring  matter,  and  that 
when  the  blue  came  to  be  afterwards  added,  its  parti- 
cles found  spaces  sufficient  to  lodge  themselves  collate- 
rally, without  being  placed  upon  the  yellow  particles. 

Several  attempts  have  been  made  to  arrange  and 
class  the  different  species  of  colouring  matters  employ- 
ed for  dyeing  and  calico-printing;  but  none  seems  to 
accord  with,  or  give  just  ideas  of,  their  several  natures 
and  properties.  M.  BerthoUet,  indeed,  alleges  sufficient 


Philosophy  of  Permanent  Colours,  87 

reasons  for  not  dividing  these  matters,  as  Mr.  Macquer 
did,  into  extractive  and  resinous,  and  also  for  not  mak- 
ing their  effects  depend,  as  Mr.  Poerner  has  done,  upon 
the  mucilaginous,  earthy,  saline,  resinous,  or  oily  parts 
of  which  they  were  supposed  to  be  compounded,  but 
without  proposing  any  suitable  arrangement  of  his  own. 

To  me,  however,  colouring  matters  seem  to  fall^na- 
turally  under  two  general  classes;  the  first  including 
those  matters  which,  when  put  into  a  state  of  solution, 
may  be  fixed  with  all  the  permanency  of  which  they 
are  susceptible,  and  made  fully  to  exhibit  their  colours 
in  or  upon  the  dyed  substance,  without  the  interposi- 
tion of  any  earthy  or  metallic  basis;  and  the  second, 
comprehending  all  those  matters  which  are  incapable  of 
being  so  fixed,  and  made  to  display  their  proper  colours, 
without  the  mediation  of  some  such  basis.  The  colours 
of  the  first  class  I  shall  denominate  substantive;  using 
the  term  in  the  same  sense  in  which  it  was  employed 
by  the  great  Lord  Verulam,  as  denoting  a  thing  solid 
by,  or  depending  only  upon,  itself;  and  colours  of  the 
second  class  I  shall  call  adjective,  as  implying  that  their 
lustre  and  permanency  are  acquired  by  their  being  ad- 
jected upon  a  suitable  basis. 

Earthy  and  metallic  bases  when  thus  interposed, 
serve  not  only  as  a  bond  of  union,  between  the  colour- 
ing matter,  and  the  dyed  substance,  but  they  also  modi- 
fy (as  well  as  fix)  the  colour;  some  of  them,  particularly 
the  oxide  of  tin,  and  the  earth  of  akim,  exalting  and 
giving  lustre  to  most  of  the  colouring  matters,  with 
which  they  are  united;  whilst  others,  and  especially  the 
oxide  of  iron,  blacken  some,  and  darken  almost  all  such 
matters,  if  made  to  combine  with  them. 

Substantive  colouring  matters  are  but  few  in  number, 
because  a  few  only  of  the  substances  employed  in  dyeing, 
.possess  such  decidedly  energetic  affinities,  as  to  be  able 


S8  Philosophy  of  Permanent  Colours. 

to  contract  a  permanent  union  with  the  stuffs  to  be 
dyed,  merely  by  being  applied  to,  or  brought  into  con- 
tact with  them.  This  is  more  especially  true  of  linen 
and  cotton;  for  in  regard  to  wool,  several  of  the  adjec- 
tive colouring  matters,  particularly  those  of  Madder, 
Cochineal,  Kermes,  and  Lac,  are  so  much  attracted  by 
it,  that  with  the  aid  of  boiling  water  they  fix  themselves 
in,  or  to,  the  fibres  of  wool,  so  as  to  produce  colours  of 
some,  though  less  durability,  than  those  which  would 
have  been  produced  if  a  basis  of  alumine,  or  the  oxide 
of  tin,  had  been  also  applied;  and  without  such  basis, 
these  colours  never  rise  so  high,  or  acquire  so  much 
lustre,  as  they  would  have  done  therewith. 

Of  substantive  colours,  I  shall  first  notice  the  animal, 
next  the  vegetable,  and,  lastly,  the  mineral. 


Philosophy  of  Permanent  Colours.  89 


CHAPTER  IV. 


Of  Substantive  Animal  Colours^  and  principally  of  the 
Tyrian  Purple.  ^ 


Tyrioque  arclebat  mwrzce  Ian  a." — Virsr.  JEneid^  lib.  iv. 


**  'RuK  fasces  secures  que  Romajice  viamfaciiint:  ideraque  pro  viajestate  pueritiae 
est:  distinguit  ab  equite  Curiam:  Diis  advocatvr  placandls:  omnemtiue  vestem  illu- 
Kiinat:  in  triumphaU  miscetnv  nuro:  qua  propter  excusata  et  purpiine  sit  insania." — 
Caii  Plinii  secuiidi  Hist.  Lib.  ix.  cap.  36. 

This,  during  many  ages,  was  the  most  celebrated,  and 
venerated  of  all  the  colours  given  by  dyeing;  and  among 
the  rich  and  beautiful,  it  seems  to  have  been  the  first 
which  mankind  were  enabled  to  fix  permanently  on 
wool,  and  linen.  It  was  obtained  from  a  whitish  half- 
fluid  matter,  secreted  by  particular  organs  in  certain 
univalvular  shell  fish,  and  retained  in  an  appropriated 
receptacle,  with  which  they  were  each  naturally  pro- 
vided; though  we  are  completely  ignorant  of  any  bene- 
fit which  this  secretion  produced  to  the  fish  themselves* 

There  is  much  obscurity,  and  some  inconsistenc}-, 
in  the  accounts  transmitted  by  ancient  writers  of  the 
shell  fish,  which  afforded  the  purple  dye.  Those  of  Pli- 
ny are  the  most  copious  and  intelligible,  though  they 
are  sometimes  at  variance  with  each  other.  He  mentions 
these  fish  under  the  several  names  of  Conchylium,  Mu- 
rex.  Purpura,  and  Buccinum;  and  these  several  names 
have  been  also  employed  by  other  Latin  authors.  But 
Fabius  Columna,  a  noble  Neapolitan,  who  first  publish- 
ed figures  of  plants,  from  engravings  made  by  his  own 
hand,  and  wrote  a  learned  dissertation  de  purpura^ 
(printed  at  Rome  in  1616)  after  much  pains  employed, 
to  elucidate  and  reconcile  the  difterent  passages  of  an- 
cient writers  on  this  subject,  thinks  himself  warranted 
to  conclude  that  there  were  but  two  kinds  or  genera  of 
these  fish,  viz.  the  purpura  and  the  buccinum:  that  the 

Vol.  I.  M 


90  Philosophy  of  Permanent  Colours, 

term  conchylium^  signified  generally  all  the  species  of 
purpurae,  and  that  it  was  also  used  sometimes  to  signify 
the  purple  colour  itself;  that  Pliny  employed  it  in  the 
former  sense,  in  the  41st  chapter  of  his  9th  book,  and 
in  the  latter,  in  the  36th  chapter  of  the  same  book;  diat 
the  term  murex,  was  also  used  as  a  generic  name  for 
the  purpuras;  and  consequently  that  both  conchylium, 
and  murex,  were  synonymous,  of  the  purpura;  "  qua- 
rum  alterum  a  conchis  nomen,  alterum  ab  aculeis,  qui 
alio  nomine  murices  dicuntur."  I  am  afraid,  however, 
that  Pliny  was  neither  constant  nor  correct  in  using 
these  names,  even  in  the  ways  by  which  Columna  en- 
deavours to  render  him  consistent  and  intelligible:  for 
in  the  chapter  last  quoted,  he  mentions  the  purpuras, 
and  the  murices,  as  being  different  fish,  and  compares 
their  respective  habits,  &c.,  adding  as  a  peculiarity  of 
the  former,  *'  Sed  purpuras  florem  ilium  tingendis  ex- 
petitum  vestibus,  in  mediis  habent  faucibus:  liquoris 
hie  minimi  est  in  Candida  vena,  unde  pretiosus  ille 
bibitur  nigricantis  rosae  colore  sublucens."  It  seems 
probable  that  the  term  murex,*  was  in  this  instance 
erroneously  substituted  for  buccinum;  as  he  proceeds 
to  state  that  all  the  shell  fish  yielding  the  purple,  or 
other  lighter  colours  of  the  conchylia,  are  in  matter  the 
same,  and  differing  only  in  temperament;  that  they  are 
of  two  kinds,  ("duo  sunt  genera")  one  which  is  the 
lesser  kind,  being  called  buccinum,  from  its  likeness  to 
the  horn  or  cornet,  so  named  and  employed  to  produce 
sound  by  blowing  through  it  ("quo  sonus  editur.") 
These  last  he  describes  as  being  round  at  the  aperture, 
with  a  serrated  margin.  The  other  kind,  says  he,  is 

*  "  Murex  cochlea  est  maris,  dicta  ab  acuqdine  et  asperitate  quae 
alio  nomine  conchylium  nominatur,  propter  quod  circumcisa  ferro, 
lacrymas  coloris  purpurei  emitlat,  ex  quibus  purpura  tingitur,  inde 
ostrum  appellatum,"  &c Isidorus,  lib.  2.  Origin,  cap.  6. 


Philosophy  of  Permanent  Colours.  91 

called  purpura,  and  has  a  projecting  pipe-shaped  beak 
(rostrum)  with  a  lateral  winding  cavity,  through  which 
it  puts  forth  its  tongue;  the  body  of  the  shell  is  more- 
over muricated,  or  armed,  even  to  its  upper  pointed 
extremity,  with  rows  of  spines,  seven  in  number;  which 
are  wanting  in  the  buccinum.  This  last,  he  adds,  ad- 
heres to  rocks  and  large  stones,  whence  it  can  alone  be 
collected. 

In  the  same  chapter,  Pliny  tells  us,  that  the  best  pur- 
puras found  in  Asia,  were  those  taken  in  the  sea  ad- 
joining to  Tyre:  that  in  Africa  the  most  esteemed  were 
those  of  Meninx  (Meninge,)  and  the  sea  coast  of  Ge- 
tulia:  and  in  Europe  those  of  Laconica.  He  adds  that 
the  Tyrians,  when  they  caught  any  of  the  greater  pur- 
puras, took  the  fish  out  of  their  shells,  the  better  to 
extract  the  colouring  matter,  but  that  they  obtained  it 
from  the  smaller  by  grinding  them  in  mills.  That  the 
fishermen  endeavoured  to  take  the  purple  fish  alive, 
because  it  otherwise  ejected  and  lost  its  precious  liquor, 
together  with  its  life.  But  on  this  point  he  seems  to 
have  been  misinformed,  there  being  good  reason  to 
believe  that  this  fish  never  ejects  the  liquor  in  question. *^ 
He  adds,  moreover,  that  this  fish  dies  speedily,  if  put 
into  fresh  water,  but  that  it  will  otherwise  live  upon  its 
own  saliva,  fifty  days  after  being  taken. 

In  the  next  chapter,  Pliny  tells  us,  that  the  purpuras 
were  also  called  pelagice,  (probably  from  their  inhabit- 
ing the  ocean)  and  that  there  were  several  varieties  of 
them,  named  difterently  from  the  places  where  they 
were  found,  and  the  food  on  which  they  subsisted;  and 

*  This  is,  at  least,  true  of  buccinum,  whose  colouring  matter  I 
found  unaltered  some  days  afler  the  fish,  or  Umax  had  died  slowly, 
by  being  kept  seven  or  eight  weeks  without  water,  and  it  was  not 
until  putrefaction  had  made  a  sensible  progress,  that  the  colouring; 
matter  became  incapable  of  producing  its  proper  effect. 


92  Philosophy  of  Permanent  Colours. 

he  afterwards  describes  the  manner  in  which  they  were 
caught.  In  his  38th  chapter,  he  states,  that  when  the 
purpuras  were  caught,  the  white  vein  or  receptacle,  be- 
fore described,  w^as  taken  out,  and  laid  in  salt  for  J^hree 
days,  after  which  a  sufficient  quantity  of  the  matter  so 
extracted  and  salted,  was  boiled  slowly  in  leaden  ves- 
sels, over  a  gentle  fire,  the  workmen  from  time  to  time 
skimming  off  the  fleshy  impurities:  this  process  lasted 
ten  days,  after  which  the  liquor  was  tried  by  dipping 
wool  into  it,  and  if  the  colour  produced  by  it  was  de- 
fective, the  boiling  was  renewed.  Pliny  afterwards  er- 
roneously represents  the  liquor  of  the  buccinum  as  only 
yielding  a  fugitive  colour;  and  says  it  was  commonly 
mixed  with  more  than  half  as  much  of  the  liquor  of  the 
pelagium,  which  of  itself  gave  a  very  dark  purple;  and 
that  being  so  mixed  these  liquors  improved  each  other, 
the  latter  giving  permanency  to  the  former,  and  being 
in  return  brightened  and  enlivened  by  it;  and  thus  pro- 
ducing a  most  beautiful  amethyst  colour.  ("  Amethysti 
color  eximius  ille.'*)  He  adds,  that  the  Tyrians  pro- 
duced their  purple,  by  first  dyeing  the  wool  with  the 
unprepared  or  greenish  liquor  of  the  pelagium,  and  af- 
terwards in  the  liquor  of  the  buccinum,  and  that  this 
colour  was  deemed  most  perfect,  when  it  resembled 
the  colour  of  coagulated  blood,  Sec.  "  Laus  ei  summa 
color  sanguinis  concreti,  nigricans  aspectu,  idemque 
mspectu  refulgem:  unde  et  homerus  purpureus  dicitur 
sanguis." 

In  his  forty- first  chapter,  Pliny  farther  tells  us,  that 
it  not  being  thought  sufficient  to  transfer  the  colour  of 
the  amethyst  to  wool,  it  had  become  the  practice  to  dye 
the  latter  again,  with  the  Tyrian  purple,  that  it  might 
obtain  a  compound  name  (Tyriamethystus,)  corres- 
ponding with  this  double  luxury:  and  that  being  satu- 
rated with  colour  of  the  conchylium,  it  was  deemed 


Philosophy  of  Permanent  Colours.  93 

fitter  to  receive  the  Tyrian  dye.  He  adds,  that  not  con- 
tent with  thus  combining  colours  obtained  from  the 
ocean,  recourse  was  also  had  to  those  produced  on  the 
land;4and  that  wool,  or  cloth,  dyed  crimson,  from  the 
coccus  (kermes,)  was  afterwards  made  to  imbibe  the 
Tyrian  purple,  in  order  that  it  might  assume  the  colour 
which  was  named  hysginus^  after  a  flower  so  called;  this 
colour  partook  greatly  of  the  crimson  tint.  But  besides 
the  coccus  (kermes,)  other  colouring  matters  were  em- 
ployed, sometimes  to  economize,  and  at  others  to  vary 
the  effects  of  the  liquors  of  the  purpura  and  buccinum; 
and  more  especially  that  of  the  lichen  roccella,  or  archil, 
which  Pliny  mentions  under  the  name  difucus  mariniis, 
and  which,  even  at  this  time,  is  greatly  employed  in 
dyeing,  though  its  beautiful  purple  colour  fades  rapidly. 
Indeed,  this  lichen,  or  moss,  was  in  such  general  use  as 
a  dye,  at  and  before  the  time  when  Pliny  wrote,  that  its 
nameyj/^-w^  came  at  length  to  signify  generally,  colours 
given  by  dyeing;  of  this,  among  numerous  other  in- 
stances, may  be  quoted  the  following  line,  by  Catullus 
(de  Nuptiis  Pelei  et  Tetidos,)  viz. 

"  Tincta  tegit  roseo  conchylis  purpura  fuco." 

Of  this  fucus,  that  from  Crete  was  the  most  esteemed. 

PUny  tells  us  also,  Lib.  xxii.  cap.  17,  that  the  alka- 
net  root,  (anchusa  tinctoria)  was  likewise  employed  as 
a  ground  for  the  purple  dye. 

By  these  and  other  means,  the  purple  colour  was 
made  to  assume  a  variety  of  shades,  some  inclining 
more  to  the  blue,  and  others  more  to  the  crimson.  The 
principal  of  these  varieties  were  noticed  by  Pliny,  in  the 
eighth  chapter  of  his  twenty-first  book,  when,  after 
mentioning  the  luxurious  art  by  which  men  had  sur- 
passed the  savour  of  natural  fiowers^  by  artificial  odours, 
he  adds,  that  they  had  also  learned  by  dyeing,  to  emu- 


94  Philosophy  of  Permanent  Colours. 

late  the  finest  colours  of  these  flowers;  and  that  of  these 
beautiful  dyes  there  were  three  divisions;  one  in  which 
the  coccus  (kermes)  was  employed,  and  which  equalled 
the  brightest  colour  of  the  rose,  (*'  qui  in  rosis  micat;") 
and  here  he  observes,  that  nothing  could  be  more 
grateful  to  the  sight,  than  the  Tyrian  and  Laconican 
purples,  especially  when  twice  dyed  (dibaphasque."*) 
In  the  second  division  he  mentions  the  amethyst,  in- 
clining to  the  violet;  and  also  the  purple  called  janthi- 
nus.f  His  third  division  includes  the  colour  strictly 
called  conchylium,  of  various  tints;X  one  resembling 
the  heliotrope  or  turnsole,  of  which,  says  he,  there  are 
several  shades;  another  approaching  the  mallow,  with  a 
mixture  of  purple,  and  a  third,  resembling  the  later 
violet,  (*^  viola  serotina,"  probably  the  purple  stock 
gilly-flowen)  this  he  mentions,  as  being  the  richest  co- 
lour that  could  be  obtained  from  the  purple  shell  fish: 
and  thus,  says  he,  nature  and  art  striving  against  each 

*  Horace  alludes  to  this  twice  dyed  purple,  (purpura  di  baplia) 
in  the  following  lines. 

*'  Te  bis  afro  murice  tinctse  vestiunt  lanae" — and 
"  Muricibus  tyriis  iterate  vellera  lanae." 
t  The  amethyst  purple  was  lighter,  and  partook  more  of  the  blue 
tint  than  the  dark  Tyrian  dibapha:  that  variety  of  il  called  janthi- 
nus  was  so  named  from  ja,  a  species  of  violet. 
%  Lucretius  de  rer.  nat.  1.  vi.  says  of  this  colour: 

"  Purpureusque  color  conchyli  jungitur  una, 
Corpore  cum  lana." 
It  was  lighter  and  had  less  body  than  the  Tyrian  purple,  being 
dyed  with  half  the  quantity  of  the  liquor  of  the  purpura;  it  also  in- 
clined more  to  the  blue,  -whence  it  frequently  acquired  the  names 
of  hyacinthus,  and  caeruleus;  and,  from  its  having  less  body,  those 
of  color  dilutus,  and  ablutus;  which  last  word  by  abbreviation  is 
supposed  to  have  produced  that  oHlutus;  whence  the  French  bleu^ 
the  English  blue,  and  the  German  blau.  Braun  says  this  colour  is 
called  thechelet  in  the  Hebrew  Bible,  and  the  shell  fish  producing 
it  chilzon.  Braun  de  vests.  Sacerd.  Hebrseor.  i.  12. 


Philosophy  of  Permanent  Colours,  95 

other,  maintain  an  equal  conflict.  "  Paria  nunc  compo- 
nuntur,  et  natura  atque  luxuria  depugnant." 

Various  (and  probably  fabulous)  accounts  of  the  first 
discovery  of  this  purple,  have  been  related  by  different 
writers.  One  of  these  ascribes  it  to  a  dog,  who,  when 
following  the  nymph  Tyros,  and  a  certain  Hercules  her 
lover,  along  the  sea  shore,  caught  one  of  the  purpuras 
lying  on  the  sand,  and  breaking  the  shell  with  his  teeth, 
his  mouth  became  coloured  with  the  purple  juice,  which 
the  nymph  observing,  expressed  a  strong  desire  to  ob- 
tain a  dress  dyed  of  this  colour.  And  the  lover  anxious 
to  satisfy  her  desire,  discovered  by  a  proper  examina- 
tion, how  this  beautiful  purple  might  be  obtained,  and 
communicated  by  dyeing.^  And  the  nymph,  by  whom 
the  purple  so  discovered  was  first  worn,  being  named 
Tyros,  the  colour  is  supposed  to  have  thence  obtained 
the  appellation  of  Tyrian  purple.  Others  have  related, 
that  this  discovery  was  made  by  the  Phoenician  Hercu- 
ks,t  and  afterwards  communicated  it  to  the  king  of 

*  See  Cassiodorus,  lib.  i.  and  Julius  Pollux,  lib.  i.  4.;  from  the 
latter,  Polydore  Virgil  has  taken  the  story. 

t  Sir  Christopher  Hawkins,  in  his  "  Observations  on  the  tin  trade 
in  Cornwall,"  (lately  published)  mentions  this  Hercules,  as  one 
said  to  have  been  the  greatest  Phoenician  navigator,  "  and  the  first 
who  brought  tin  from  the  Cassiterides,  or  British  isles:"  and,  ad- 
verting to  the  story  of  his  having  also  "  invented  the  ahell  fiurfile^ 
by  accidentally  remarking  that  a  dog's  mouth  was  stained  there- 
with," he  observes,  that  "  as  both  these  discoveries  are  attributed 
to  the  same  person,  we  may  thence  infer,  that  the  tin  of  Britain 
was  an  essential  ingredient  in  fixing  the  fine  purple  dyes  of  the 
ancients;  or,  (adds  Sir  Christopher,)  as  Mr.  Polwhele  elegantly 
expresses  it,  "  very  possibly  the  purple  dye  of  the  Tyrians,  gained 
its  high  reputation  among  the  ancients,  from  the  use  of  our  tin,  in 
the  composition  of  the  dye  stuff,  as  the  tin  trade  was  solely  in  their 
own  management."  On  this  subject,  however.  Sir  Christopher, 
perhaps,  from  a  partiality  in  him,  both  natural  and  excusable,  to- 
wards Cornwall,  has  departed  from  his  usual  logical  accuracy,  and 


96  Philosophy  of  Permanent  Colours. 

Phoenicia,  who  thereupon,  immediately  began  to  wear 
purple.  (See  Goguet,  1.  ii.  ch.  2.)  That  this  colour  first 
became  known  at  the  city  of  Tyre,  and  thence  obtained 
its  name,  is  rendered  probable  by  the  fact,  of  its  having 
also  borne  the  appellation  of  Sarranus,  from  Sarra^  the 
name  by  which  that  city  had  been  previously  distin- 

hazarded  an  inference  which  his  premises  do  not  warrant;  for 
though  it  were  true,  that  tin  was  first  carried  to  Tyre,  and  the 
shell  purple  first  discovered  there,  by  the  same  fierson;  we  should 
have  no  right  to  conclude  that  the  former  was  necessarily  employ- 
ed to  produce  the  latter;  and  there  is  not  only  no  evidence  that 
this  ever  was,  but  on  the  contrary,  many  facts  prove  that  it  never 
could  have  been  the  case;  indeed,  my  own  experiments  will  show, 
that  the  colourable  matter  of  the  buccinum  attains  its  beautiful 
purple,  and  fixes  itself  permanently,  without  any  other  aid  than 
that  of  solar  light,  and  also  that  solutions  of  tin  are  completely  use- 
less for  either  of  these  purposes:  nor  is  there  the  smallest  reason 
to  suspect  that  they  ever  were  employed  for  dyeing,  until  the  se- 
venteenth century. 

In  another  paragraph,  which  Sir  Christopher  has  subsequently 
quoted  from  Mr.  Polwhele,  the  latter  supposes,  that  the  Phoeni- 
cians must  have  known  the  use  of  tin,  "  as  one  of  the  non-colour- 
ing retentive  ingredients;"  because,  "  it  is  not  likely  that  the  sim- 
file  blood  of  the  shell  Jiah^  hoivever  beautiful  at  firsts  could  have 
proved  a  lasting  dye;**  and,  therefore,  he  imagines,  that  "  some 
retentive  ingredients,"  (like  "  tin  dissolved  in  aqua  fortis,")  "  must 
have  been  necessary  to  secure  its  brightness^  and  preserve  its  beau- 
ty."—-The  "  brightness  and  beauty  of  the  **  simfile  blood  of  a  shell 
fish!!**  Of  the  '^^ purpura  **  and  the  buccinum!!!  As  well  might 
Mr.  Polewhele  expatiate  on  the  brightness  and  beauty  of  the  sim- 
ple blood  of  the  oyster  and  the  snail;  and  suppose  that  by  the  help 
of  tin,  they  would  produce  the  Tyrian  purple.  How  an  idea  so  ex- 
travagant, and  so  indicative  of  gross  inattention  to  the  common 
productions  of  nature,  could  have  occurred  to  this  gentleman,  I 
know  not,  unless  he  derived  it  from  the  following  lines  of  Mar- 
tial, viz. 

"  Sanguine  de  nostro  tinctas,  Ingrate,  lacernas 
Induis;  et  non  est  hoc  satis:  esca  sumus.*' 


Philosophy  of  Permanent  Colours.  97 

guished;   and,  hence  the  following  line  of  Virgil,  (2 
Georg.  506.) 

"  Ut  gemma  bibat,  et  Sarrano  dormiat  Ostro.^* 

Respecting  the  time  when  this  discovery  was  first  made, 
the  more  ancient  writers  do  not  agree,  some  stating  it  to 
have  been  about  1500  years  previous  to  the  Christian  aera, 
and  others  almost  a  century  later,  whilst  Minos  reigned 
in  Crete. 

Pliny  appears  to  think,  that  purple  had  been  worn  at 
Rome,  soon  after  the  building  of  that  city,  but  that  even 
Romulus  never  wore  it,  except  in  his  trabea,  or  regal 
mantle:  and  he  states,  as  a  certain  fact,  that  TuUus  Hos- 
tilius  was  the  first  king  of  Rome,  who  assumed  the  pre- 
fe-x^a  or  long  robe, with  ^roac/ purple  stripes,  after  having 
subdued  the  Tuscans.  He  adds,  "  Nepos  Cornelius,  who 
died  in  the  reign  of  Augustus  Caesar,  when  I  was  a  young 
man,  assured  me  that  the  light  voilet  purple  had  been 
formerly  in  great  request,  and  that  a  pound  of  it  was  com- 
monly sold  for  100  denaria,  (nearly  41.  sterling:)  that  soon 
after  the  tarentine  or  reddish  purple  came  into  fashion; 
and  that  this  was  followed  by  the  Tyrian  dibapha,  which 
could  not  be  bought  for  less  than  1000  denaria,  (almost 
40/.  sterling)  the  pound;  which  was  its  price  when  P.  Len- 
tulus  Spinter  was  iEdile,  Cicero  being  then  Consul.  But 
after  this,  the  double-dyed  purple  became  less  rare,  &c." 
See  lib.  ix.  c.  39. 

As  soon  as  mankind  were  acquainted  with  the  purple 
as  a  dye,  they  seem  to  have  considered  it,  not  only  as  being 
of  all  others  the  most  estimable  in  itself,  but  also  the  most 
acceptable  to  the  gods.  It  was,  therefore,  naturally  ap- 
propriated  to  the  services  of  religion,  and  of  its  ministers, 
as  well  as  to  distinguish  the  highest  civil  and  military  dig- 
nities. Pliny  has  noticed  the  use  made  of  it  by  Romulus, 
and  succeeding  kings  of  Rome,  as  well  as  afterwards  by 

Vol.  I.  N 


98  Philosophy  of  Permanent  Colours, 

the  consuls,  and  higher  magistrates  of  the  republic.  Under 
the  Roman  Emperors,  it  became  the  peculiar  emblem, 
or  symbol  of  majesty,  and  the  wearing  of  it  by  any  who 
were  not  of  the  Imperial  family,  was  deemed  a  treasonable 
usurpation,  punishable  by  death;  as  was  mentioned  by 
Suetonius.  (Vita  Neronis.)  Hence  the  expressions  of 
"  sacer  murex,"  and  of  "  adorare  piirpura?n,^^  in  the  Ro- 
man  laws.  (See  BischofF  Versuche,  &c.) 

When  so  much  importance  and  sanctity  (if  I  may  use 
this  expression,)  had  been  attached  to  this  colour,  the  dye- 
ing of  it  was  confined  to  a  few  particular  places,  and  also 
to  a  few  persons  called  muricileguli;  and  we  need  not 
therefore  wonder,  that  after  the  Greek  empire  had  been 
overthrown,  the  knowledge  of  the  shell-fish  affording  the 
purple  colour,  as  well  as  the  ways  of  employing  them  as  a 
dye,  should  have  been  completely  lost  in  the  12th  century; 
and  that  afterwards,  when  learning  began  to  revive,  some 
persons  should  have  doubted,  whether  either  of  these  had 
ever  existed;  nor  need  we  wonder,  after  this  loss,  that  the 
high  pre-eminence  which  had  belonged  to  the  purple,  was 
in  a  considerable  degree  transferred  to  the  scarlet,  afforded 
by  the  kermes;  which  after  being  called  red  purple ^  at 
length  obtained  the  name  (unknown  to  the  ancients)  of  j^ar- 
let,^  as  we  learn  among  others  from  Caneparius,  who  in 
his  work  de  Atramentis,  p.  207,  after  mentioning  that  the 
ancient  purple  then  unknown,  had  formerly  distinguished 
emperors,  kintj;s,  &c.  adds,  '*  Nostra  autem  setate  (the 
beginning  of  the  17th  century)  hujuscemodi  vestes  vo- 
cantur  scarlati,  quibus  Venetiis  illustrissimi,  Senatores 
procedere  conspiciuntur." — Again,  in  the  next  page 
he  says,  "  Quamobrem  ubique,  et  Venetiis  praesertim 

*  This  colour  afterwards  obtained  the  name  of  Venetian  scarlet,  to 
distinguish  it  from  the  brighter  colour,  now  called  scarlet,  and  which 
had  never  been  seen  until  Cochineal,  and  the  effect  of  solutions  of 
tin  upon  its  colouring  matter,  were  discovered,  about  the  year  1630. 


Philosophy  of  Permanent  Colours,  99 

maxlme  existimatur  purpura,  vulgari  dictione,  dicta  es- 
carlatum^  pro  illustrissimis  patriciis  insigniendis."  He 
mentions  also  that  the  violet  purple  was  then  commonly 
called  "  el  Pavonazzo^'*''  by  the  Italians.  It  was  probably 
then  dyed  from  archil  only. 

It  happened,  however,  more  than  sixty  years  after  the 
work  of  Canniparius  had  been  printed  at  Venice,  that 
Mr.  William  Cole,  of  Bristol,  being  at  Minehead  (viz. 
in  1683,)  he  was  there  told,  of  a  person  living  at  a  sea- 
port in  Ireland,  "  who  made  considerable  gain  by  mark- 
ing, with  a  delicate  durable  crimson  colour,  the  fine 
linen  of  ladies  and  gentlemen,  sent  to  him  for  that  pur- 
pose;" and  that  this  colour  was  "  made  by  some  liquid 
substance,  taken  out  of  a  shell-fish."  Mr.  Cole  being  a 
lover  of  natural  history,  and  having  his  curiosity  thus  ex- 
cited, went  in  quest  of  these  shell- fish;  and  after  trying 
various  kinds  without  success,  he  at  length  found  consi- 
derable quantities  of  a  species  of  buccinum  on  the  sea- 
coasts  of  Somersetshire,  and  the  opposite  coasts  of  South 
Wales;  and  after  many  ineffectual  endeavours,  he  dis- 
covered the  colouring  matter  placed  in  a  *'  white  vein, 
lying  transversely  in  a  little  furrow,  or  cleft,  next  to  the 
head  of  the  fish;"  which  says  he,  "  must  be  digged  out 
with  the  stiff  point  of  a  horse- hair  pencil,  made  short  and 
tapering,  by  reason  of  the  viscous  clamminess  of  the  white 
liquor  in  the  vein,  that  so  by  its  stiffness  it  may  drive  in 
the  matter  into  the  fine  linen,  or  white  silk,"  intended  to 
be  marked.  Letters  or  marks  made  in  this  way,  with  the 
white  liquor  in  question,  *Svill  presently,''  adds  he, 
^*  appear  of  a  pleasant  green  colour,  and  if  placed  in  the 
sun,  will  change  into  the  following  colours,  u  e,  if  in  the 
winter,  about  noon,  if  in  the  summer,  an  hour  or  two 
after  sun-rise,  and  so  much  before  setting  (for  in  the  heat 
of  the  day  in  summer  the  colours  will  come  on  so  fast, 
that  the  succession  of  each  colour  will  scarce  be  distin- 


100  Philosophy  of  Permanent  Colours, 

guishable;)  next  to  the  first  light  green,  will  appear  a 
deep  green;"  *' and  in  a  few  minutes  this  will  change 
into  a  full  sea  green;  after  which,  in  a  few  minutes  more, 
it  will  alter  into  a  watchet  blue;  from  that,  in  a  little  time 
more,  it  will  be  of  a  purplish  red;  after  which,  lying  an 
hour  or  two  (supposing  the  sun  still  shining,)  it  will  be 
of  a  very  deep  purple  red;  beyond  which  the  sun  can  do 
no  more."  He  remarks,  however,  "that  these  changes 
are  made  faster  or  slower,  according  to  the  degree  of  the 
sun's  heat;"  ''but  then,"  adds  he,  '*the  last  and  most 
beautiful  colour,  after  washing  in  scalding  water  and  soap, 
will  (the  matter  being  again  put  out  into  the  sun  or  wind 
to  dry)  be  much  a  differing  colour  from  all  those  men- 
tioned, i.  e,  a  fair  bright  crimson,  or  near  to  the  Prince's 
colour;  which  afterwards,  notwithstanding  there  is  no 
styptic  to  bind  the  colour,  will  continue  the  same,  if  well 
ordered,  as  I  have  found  in  handkerchiefs  that  have  been 
washed  more  than  forty  times;  only  it  will  be  somewhat 
allayed  from  what  it  was,  after  the  first  washing."  Mr. 
Cole  found,  that,  if  linens  marked  with  the  white  liquor 
in  question  were  taken  out  of  the  sun,  when  the  colours 
had  only  reached  any  one  of  the  before  mentioned  shades, 
and  shut  up  betw^een  the  leaves  of  a  book,  the  colour  or 
colours  made  no  farther  progress  whilst  so  shut  up,  but 
remained  always  of  the  same  shade.  He  also  founds  that 
whilst  linen  marked  with  the  white  liquor  was  drying  by 
exposure  to  the  sun,  for  the  first  time,  it  would  always 
"  yield  a  very  strong  foetid  smdl  (which  divers  who  smelt 
it  could  not  endure,)  as  if  garlick  and  assafoetida  were 
mixed  together;"  and  this  happens  in  cases  where  linen, 
after  being  marked,  had  been  shut  up  in  a  book  for  twelve 
months,  before  it  was  exposed  to  the  sun's  rays.  He  also 
found,  that  the  colour  in  linen  which  had  been  dried,  and 
washed  immediately  after  being  marked,  was  better  than 
when  it  had  lain  fourteen  months  between  the  leaves  of  a 
book,  unwashed. 


Philosophy  of  Permanent  Colours.  101 

Mr.  Cole  sent  some  of  the  first  linen  marked  by  him 
in  this  way,  to  Dr.  Plot,  then  one  of  the  Secretaries  of 
the  Royal  Society,  in  November,  1684;  and  it  was  soon 
after  shown  to  king  Charles  the  Stcond,  who  admired  it 
greatly,  and  desired  that  some  of  the  shell-fish  might  be 
collected  and  brought  to  town,  that  he  might  see  the 
liquor  applied,  and  the  successive  changes  of  colour  which 
it  underwent;  but  before  this  could  be  done,  the  king 
died;  and  though  Mr.  Cole's  letter  (from  which  the  pre- 
ceding extracts  were  made)  was  in  the  following  year 
published,  in  the  fifteenth  volume  of  the  Philosophical 
Transactions,  and  excited  the  attention  of  philosophers 
in  most  of  the  countries  of  Europe,  it  does  not  appear 
that  any  attempt  was  made  to  revive  the  practice,  along 
with  the  knowledge,  of  dyeing  the  ancient  purple. 

After  an  interval  of  twenty-four  years,  M.  Jussieu 
found  a  small  species  of  buccinum,  in  form  resembling 
the  garden  snail,  on  that  part  of  the  French  coast 
which  is  washed  by  the  Atlantic  ocean,  and  presented 
some  of  them,  in  the  year  1709,  to  the  Royal  Academy 
of  Sciences  at  Paris;  and  in  the  following  year,  the 
celebrated  M.  Reaumur  found  great  quantities  of  the 
buccinum  on  the  coast  of  Poitou;  and  he  morever  ob- 
served, that  the  stones,  and  little  sandy  ridges  round 
which  these  shell-fi  ^  had  collected,  were  covered  with  a 
kind  of  oval  "  graines,"  some  of  which  were  white,  and 
others  of  a  yellowish  colour;  and  having  collected  and 
squeezed  some  of  these  upon  the  sleeve  of  his  shirt,  so  as 
to  wet  it  with  the  fluid  or  liquor  which  they  contained, 
he  was  agreeably  surprised,  in  about  half  an  hour,  upon 
finding  it  stained  of  a  fine  purple  colour,  which  he  was 
unable  to  discharge  by  washing.  This  was  done  upon  the 
sea-shore.  He  next  collected  a  quantity  of  these  grains, 
and  carrying  them  •  his  apartment,  bruised  and  squeezed 
different  parcels  of  them  tipon  bits  of  linen;  but  to  bis 


102  Philosophy  of  Permanent  Colours. 

great  surprise,  after  waiting  two  or  three  hours,  no  colour 
appeared  upon  the  spots  wetted  with  their  liquor.  Unable 
to  conceive  the  reason  of  this  disappointment,  and  having 
almost  determined  to  return  again  to  the  sea-shore,  and 
repeat  his  experiment  in  the  same  place  as  before,  he 
chanced  to  perceive  some  purple  spots,  occasioned  by 
drops  of  the  liquor  which  had  accidentally  fallen  upon 
a  part  of  the  plaster  of  Paris  with  which  the  sides  of  the 
window  were  covered,  and  which,  hnving  been  more 
strongly  acted  upon  by  the  light,  than  the  bits  of  linen 
wetted  with  the  same  liquor  in  the  interior  part  of  the 
room,  had  become  purple,  though  the  day  was  then 
cloudy.  Without,  however,  perceiving  this  to  have  been 
the  cause  of  his  disappointment,  he  broke  off  a  bit  of  the 
same  plaster,  and  carrying  it  to  the  back  part  of  the  room, 
where  the  bits  of  linen  in  question  were  laying,  he  wetted 
it  with  the  same  liquor,  without  its  becoming  coloured. 
He  then  thought  of  carrying  the  colourless  bits  of  linen 
to  the  window,  which  w^as  open,  and  there  he  soon  per- 
ceived them  to  become  purple.  It  was  then  fashionable 
to  explain  all  effects  upon  mechanical  principles,  as  it  had 
been  at  the  time  when  he  also  endeavoured  to  account 
for  the  shock  of  the  torpedo,  as  resulting  mechanic  ally 
from  a  very  quick  stroke  given  by  the  contraction  of  par- 
ticular muscles  in  that  fish.  M.  Reaumur,  therefore,  soon 
persuaded  himself,  and  others,  that  the  bits  of  linen  which 
had  remained  colourless  whilst  at  the  back  part  of  his 
room,  were  rendered  purple  at  the  window  by  the  differ- 
ent manner  in  which  the  air  acted  upon  the  colouring 
liquor  in  the  latter;  and  that  this  difference  consisted 
solely  in  the  air's  having  greater  motion  at  the  window, 
than  at  a  distance  from  it;  and  almost  all  his  subsequent 
experiments,  seem  to  have  been  calculated  to  confirm 
this  erroneous  hypothesis. 

He  placed  bits  of  linen,  just  wetted  with  the  colouring* 


Philosophy  of  Permanent  Colours,  103 

liquor,  in  the  open  air,  and  laying  a  stone  upon  each,  he 
found  the  covered  part  remain  colourless,  whilst  the  rest 
were  made  purple;  which  he  ascribed  to  the  mechanical 
impression  of  wind,  not  considering  that  the  stones  kept 
off  the  light,  as  well  as  the  air. — Having  read  an  account 
of  Mr.  Cole's  observations,  in  the  Philosophical  Transac- 
tions, M.  Reaumur  exposed  a  bit  of  linen,  wetted  with 
the  colouring  liquor,  to  the  rays  of  the  sun,  collected  by 
a  small  burning  glass,  and  saw  it  become  purple  in  an 
instant;  and  consequently,  without  being  able  to  distin- 
guish any  of  the  changes  of  colour  through  which  it  had 
so  rapidly  passed.  Putting  another  bit  of  linen,  wetted 
with  the  same  liquor,  so  near  to  the  fire  that  it  would  have 
burned  had  it  been  dry,  he  likewise  saw  it  become  purple 
immediately;  but  with  equal  degrees  of  heat,  the  effects 
produced  by  the  sun's  rays  were  beyond  comparison  the 
greatest. 

M.  Reaumur  conceived  the  grains  in  question  to  be  the 
eggs  or  spawn  of  some  fish,  but  whether  of  the  buccinum, 
or  any  other  species,  he  was  uncertain;  and  under  this 
uncertainty  he  proposed  calling  them  *'  Oeufs  de  pour- 
pre,"  eggs  of  purple.  The  colour  which  they  produced, 
was  at  least  equal,  if  not  superior  in  beauty,  as  well  as 
durability,  to  that  of  the  buccinum;  though  the  colouring 
liquor  of  the  latter  was  much  thicker  than  that  of  the 
purple  eggs,  and  not  liable  to  pass  through  the  different 
changes  of  colours  so  quickly  as  that  of  the  eggs,  except- 
ing when  diluted.  Having  put  some  of  this  diluted  liquor 
into  two  glasses,  and  placed  one  of  them  in  contact  with 
the  sun's  rays,  and  the  other  near  the  fire,  the  former 
became  purple,  without  any  sensible  addition  of  heat, 
whilst  that  which  was  at  the  fire  had  only  began  to  ac- 
quire the  first  shade  of  colour,  though  it  was  sensibly  hot: 
and  indeed  he  always  found  the  colours  produced  by  the 
sun  to  be  more  beautiful  than  any  others;  a  circumstance 


104  Philosophy  of  Permanent  Colours. 

which  he  endeavours  to  explain,  by  supposing  its  rays  t© 
act  mechanically,  in  changing  the  figures  or  arrangements 
of  the  particles  of  the  liquor,  in  the  same  way  as  he  sup- 
posed the  wind  to  change  them,  but  with  more  efficacy. 
M.  Reaumur  perceived  the  same  disagreeable  smell  of 
garlick  from  the  liquor,  which  Mr.  Cole  had  before  men- 
tioned; and  he  found  it  the  more  insupportable,  as  the 
heat  of  the  sun  or  fire  was  the  strongest.  The  colour  of 
the  liquor  was  not  produced,  or  affected  either  by  vege- 
table alkali  (carbonate  of  potash),  or  sulphuric  acid;  but 
a  very  little  corrosive  sublimate  of  mercury,  put  into  the 
diluted  liquor  of  the  buccinum,  instantly  rendered  it  blue, 
and  the  colour  was  soon  precipitated  with  the  mercury, 
to  the  bottom  of  the  vessel,  leaving  the  liquor  colourless; 
an  cftect  which,  as  usual,  he  endeavoured  to  explain  me- 
chanically, by  supposing  the  su  I  climate  to  consist  of  little 
globules  stuck  round  with  sharp  points,  which  enabled  it 
to  change  the  arrangement  of  the  particles  of  the  liquor 
more  expeditiously,  even  than  he  had  supposed  it  done 
by  the  wind.  He  found  that  the  liquor  of  the  buccinum 
tasted  as  hot  as  the  hottest  pepper,  whilst  that  of  the 
purple  eggs  was  saltish;  but  even  this  was  so  viscid,  that 
it  did  not  run,  when  topically  applied  to  linen.  Sec;  and 
as  the  eggs  were,  according  to  M.  Reaumur's  account,* 
so  plentiful,  that  one  man  might  collect  half  a  bushel  of 
them  in  a  few  hours,  there  certainly  is  reason  to  think, 
that  they  would  be  highly  useful,  at  least  in  calico  print- 
ing, where  their  liquor  might  be  applied,  with  the  greatest 
facility,  both  for  penciling  and  printing,  as  a  substantive 
topical  colour,  and  where  a  small  quantity  would  go  far, 
especially  upon  fine  muslins.  But  at  that  time  the  art  of 
calico  printing  had  not  been  practised  in  France,  and 

♦  In  the  Mem.  de  TAcad.  Royale  des  Sciences,  &c.  an.  1711. ' 


Philosophy  of  Permanent  Colours.  105 

therefore   nobody  thought  of  applying  M.   Reaumur's 
<Jiscoveries  in  that  way. 

About  the  beginning  of  the  year  1736,  M.  Duhamel 
found  the  purpura^  (the  buccinum  only  having  been  dis- 
covered by  Cole  and  Reaumur,)  in  great  abundance  upon 
tlie  coast  of  Provence;  and  observed  it  to  agree  very  well 
with  the  description  thereof,  given  by  Rondelet.  He  found 
the  viscid  colouring  liquor  of  the  fish  to  be  white,  except 
in  a  few  instances,  where  it  was  green,  which  he  suspected 
to  be  some  morbid  effect.  The  white  liquor  being  exposed 
to  the  sun's  rays,  assumed  the  following  colours;  1.  a  pale 
yellowish  green;  2.  an  emerald  green;   3.  a  dark  bluish 
green;  4.  a  blue,  with  a  beginning  redness;  and  5.  a  pur- 
ple; and  these  changes  all  happened  in  less  than  five  mi- 
nutes. Linen  wetted  with  the  white  liquor,  and  left  all  night 
in  a  dark  room,  had  only  become  green  in  the  morning; 
and  this  was  also  the  case  of  linen  wetted  in  like  manner, 
and  exposed  all  night  in  the  open  air,  but  shaded  from 
the  moon's  light.  A  piece  of  linen,  wetted  in  the  same 
manner,  being  partly  exposed  to  the  sun's  rays,  and  partly 
hid  by  a  crown-piece  of  silver,  the  former  part  became 
purple,  whilst  the  latter  was  only  green.  Other  linen  so 
wetted,  being  heated  in  a  Dutch  oven  before  the  fire,  or 
upon  a  hot  iron,  became  of  a  dark  green,  but  not  purple. 
The  fumes  of  burning  sulphur  only  produced  a  dark  green; 
and  this  was  moreover  the  case  with  the  different  coloured 
rays  of  the  sun,  applied  separately  by  a  prism.  Wishing 
to  see  whether  evaporation  tended  to  colour  the  white  li- 
quor, Mr.  Duhamel  put  some  of  it  into  a  phial  well  stop- 
ped; and,  upon  exposing  it  to  the  sun,  found  the  liquor 
become  of  a  reddish  purple  almost  immediately.  A  piece 
of  linen  wetted  and  stuck  upon  the  back  of  a  plate  of  po- 
lished glass,  three  lines  in  thickness,  and  exposed  to  the 
sun's  rays,  became  purple  even  before  it  had  dried.  Three 
pieces  of  linen  so  wetted,  being  covered,  one  with  white, 
Vol.  I.  O 


ICfe  Philosophy  of  Permanent  Colours. 

a  second  with  black,  and  the  third  with  oiled  paper,  the 
last  soon  became  of  a  good  purple  colour,  but  the  others 
only  became  green.  Linens  wetted  in  like  manner,  and  ex- 
posed to  the  light  of  the  moon,  or  of  burning  wood  or  can- 
dles, became  green,  but  not  purple.  Exposure  to  the  sun's 
rays  always  produced  the  purple,  and  most  expeditiously, 
when  its  light  and  heat  were  strongest,  the  sun- shine  of 
the  month  of  March  having  proved  much  more  efficacious 
than  that  of  January  or  February.  The  purple  was  instantly 
produced  by  the  sun's  rays,  collected  under  a  burning 
glass.  The  liquor  which  M.  Duhamel  suspected  to  be 
morbidly  green,  became  purple  sooner  than  the  white  li- 
quor; a  circumstance  which  does  not  indicate  its  green- 
ness to  have  been  the  effect  of  disease.  In  linens  where 
the  colour  had  stopped  at  the  green,  without  reaching  the 
purple  hue,  it  was  soon  cairied  off  by  boiling  with  soap, 
fossil  alkali,  alum,  &c.  which  the  colours  that  had  already 
become  purple,  withstood  for  a  long  time,  and  were  not 
hurt  by  the  fumes  of  burning  sulphur.  See  Memoirs  of 
the  Royal  Academy  of  Sciences,  Sec.  1736. 

Until  Mr.  Cole  had  discovered  the  buccinum,  no  ade- 
quate conceptions  could  have  been  formed  of  the  changes, 
through  which  its  liquor,  and  that  of  the  purpura,  became 
purple.  Aristotle  and  Pliny  had,  indeed,  both  given  inti- 
mations of  its  being  primitively  white;  and  Pliny  had 
slightly  mentioned  one  of  the  intermediate  colours,  the 
green.*  That  the  other  changes  were  not  more  distinctly 
noticed,  must  be  ascribed  to  the  little  attention  then  be- 
stowed upon  subjects  of  natural  philosophy,  and  perhaps 
to  a  want  of  sufficient  communication  with  the  purpurarii 
piscatories,  by  whom  the  liquor  was  collected  and  salted. 
And  there  can  be  no  doubt  of  the  identity  of  the  shell- fish 

*  "  Color  austerus  in  Glance,  et  h'ascenti  similis  mari."  Lib.  ix 
cap.  36. 


Philosophy  of  Permanent  Colours,  107 

employed  by  the  ancients,  and  those  discovered  by  Cole, 
Reaumur,  and  Duhamel,  or  of  the  similitude  of  their 
changes,  and  of  the  means  by  which  their  several  liquors 
became  purple.  In  a  collection  of  Anecdota  Graeca,  lately 
published  by  M.  d'Anse  de  Villoison,  from  MSS.  pre- 
served in  the  King's  library  at  Paris,  and  that  of  St.  Mark, 
at  Venice,  there  is  a  description  of  the  manner  of  catch- 
ing the  shell-fish,  employed  for  the  puq^le  dye,  written  by 
an  eye-witness,  Eudocia  Macrembolitissa,  daughter  of 
the  emperor  Constantine  the  eighth,  who  lived  in  the 
eleventh  century,  while  the  knowledge  and  practice  of 
dyeing  that  colour  for  the  use,  and  at  the  expense,  of  the 
Greek  emperors  still  subsisted;  and  from  which  it  mani- 
festly appears,  that  in  those  times,  as  well  as  in  ours,  the 
purple  did  not  acquire  its  due  lustre  and  perfection  until 
it  had  been  exposed  to  the  sun's  rays. 

Those  who  are  duly  acquainted  with  the  more  recent 
chemical  discoveries,  can  only  hesitate  between  two 
ways  of  accounting  for  the  changes  through  which  the 
liquors  of  the  purpura  and  buccinum  become  purple;  I 
mean,  whether  it  be  by  gaining  oxygene  from  the  at- 
mosphere, like  indigo,  when  it  acquires  its  blue  colour; 
or  by  the  separation  of  a  redundant  portion  of  oxygene, 
naturally  combined  for  some  unknown  purpose,  in  the 
liquor  of  these  shell-fish;  and  in  that  particular  state 
M'hich  will  not  admit  of  its  being  separated  without  the 
application  and  assistance  of  light;  as  is  also  the  case  of 
horned  silver,  rendered  purple  by  the  sun's  rays;  of 
vegetables,  rendered  green  by  the  same  cause,  after 
they  had  become  white  by  growing  in  darkness;  of 
peaches,  purple  grapes,  and  other  fruit,  which  never 
acquire  their  proper  colours  by  any  degrees  of  heat, 
but  always  remain  white  or  green,  if  shaded  and  se- 
cluded from  the  contact  of  the  sun's  rays.  A  very  few 
experiments,  which  I  hope  to  have  an  opportunity  of 


108  Philosophy  of  Permanent  Colours, 

making  hereafter,  would  ascertain  this  point  beyond 
the  possibility  of  doubt;  though  in  fact  there  is,  I 
think,  at  present,  very  little  room  to  doubt  but  that 
the  purple,  under  consideration,  is  produced  in  the  last 
of  the  two  ways  just  mentioned.* 

Such  were  the  conclusions  which  I  had  formed  and 
published  in  1794;  and  it  will  soon  be  found  that  they 
have  since  been  completely  verified,  by  the  most  deci- 
sive experiments. 

In  the  month  of  September,  1803,  Mr.  Samuel 
Richardson,  of  Cowbridge,  in  Glamorganshire,  at  the 
request  of  my  truly  respectable  friend  Dr.  Cheston,  of 
Gloucester,  obligingly  procured  and  forwarded  to  me  a 
large  parcel  of  shell-fish,  (apparently  of  that  species 
with  which  the  experiments  of  Mr.  Cole  had  been  for- 
merly made,)  belonging  to  the  genus  of  Buccinum 
(commonly  called  whelks)  and  agreeing  in  their  speci- 
fic character,  with  the  buccinum  lapillus  of  Linnaeus. 

I  had  no  difficulty  in  finding  and  extracting  the  co- 
louring matter  of  these  Testacca,  which  in  appearance 
and  consistence  very  much  resembled  well-formed  pus, 
and  was  collected  to  the  amount  of  two  or  three  drops 
in  a  little  whitish  cyst,  placed  transversely  under,  but 
in  immediate  contact  with  the  shell,  and  near  the  head 
of  its  inhabitant  the  limax.  The  white  slightly  yellowish 
colour  of  this  cyst,  and  of  the  matter  contained  therein, 
rendered  it  perceptible  by  close  inspection  through  the 
semi-transparent  substance  of  the  shell,  though  the  lat- 
ter was  not  furrowed  or  channelled,  where  the  cyst 
came  in  contact  with  it,  as  I  had  supposed  from  Mr. 
Cole's  description. 

*  M.  Berlhullet  on  the  contrary  appears  lo  believe  that  the  effect 
in  question,  is  produced  by  a  farther  combination  of  oxygene.  See 
Elements,  &c.  torn.  i.  p.  144,  last  edition. 


Philosophy  of  Permanent  Colours.  109 

This  pus-like  matter,  either  diluted  with  an  equal 
portion  of  water,  or  undiluted,  being  applied  to  bits  of 
white  linen  or  calico,  became  purple  after  going  regu- 
larly through  the  intermediate  colours  mentioned  by 
Mr.  Cole,  and  in  the  same  order.  And  these  changes 
were  completed  in  a  very  few  minutes,  when  the  sky 
was  serene,  and  the  bits  of  linen  or  calico  were,  in  sum-^ 
mer^  fully  exposed  to  the  sun's  beams;  and  more  espe- 
cially with  the  diluted  matter;  for  the  undiluted,  being 
often  confined  with  too  much  body^  in  a  small  space,  was 
not  so  soon  thoroughly  penetrated  and  changed  by  the 
solar  rays. 

I  mixed  different  parcels  of  this  matter  with  each  of 
the  several  alkalies,  both  in  their  mild  and  caustic  states, 
and  having  applied  them  to  linen  and  calico,  I  found 
that  instead  of  retarding  the  progress  of  these  changes, 
and  the  ultimate  eifect  of  a  purple  colour,  they  rather 
produced  an  acceleration  thereof:  and  this  was  the  case 
in  a  more  remarkable  degree,  when  the  matter  in  ques- 
tion was  mixed  with  alcohol,  or  the  volatile  essential 
oils  of  cajeput,  turpentine,  lavender,  &c.  or  with  mu- 
ridtic  acid:  on  the  contrary,  these  changes  appeared  to 
be  considerably  retarded,  by  the  admixture  of  nitric 
acid,  though  it  did  not  hinder  them  from  ultimately 
taking  place.  Sulphuric  acid  had  a  similar  effect,  but 
in  a  lesser  degree,  as  had  the  citric,  and  acetous  acids, 
and  that  of  tartar.  The  same  matter  applied  to  muslin, 
and  put  into  a  glass  filled  with  hydrogene  gas,  and 
closely  stopped,  being  exposed  to  the  direct  rays  of  the 
sun,  went  through  all  the  before-mentioned  changes  in 
one  third  less  time  than  usual;  whilst  similar  matter," 
confined  in  the  same  manner  with  oxygene  gas,  and  ex- 
posed at  the  same  time,  underwent  these  changes  more 
slowly:  and  nitrogene  gas  employed  in  the  same  way, 
and  at  the  same  time,  had  no  apparent  influence  upon 


110  Philosophy  of  Permanent  Colours. 

them.  These,  and  other  experiments  rendered  it  at 
least  highly  probable  that  a  separation  and  not  an  addi- 
tion of  oxygene  accompanied  and  contributed  to  the 
attainment  of  the  purple  colour  in  question.  But  before 
I  had  made  all  the  experiments  which  seemed  necessary 
to  ascertain  the  fact,  my  attention  was  unavoidably  di- 
verted to  other  objects;  and  fearing  that  my  whelks 
might  die,  and  become  unfit  for  other  experiments  be- 
fore I  could  find  leisure  to  make  those  which  1  had 
projected,  I  broke  the  shells  of  at  least  one  hundred  of 
them,  and  after  extracting  their  colouring  matter,  and 
appl}ing  it  undiluted  to  bits  of  calico  and  muslin,  I 
placed  these  bits  separately,  and  as  expeditiously  as 
possible,  each  between  two  leaves  of  a  large  blank  folio 
book,  and  afterwards  kept  it  closely  shut,  to  exclude 
the  light:  believing,  though  the  matter  in  question  had 
not  been  allowed  to  become  dry  before  it  was  shut  up 
in  this  way,  that  so  much  of  its  moisture  would  be 
absorbed  by  the  paper,  as  to  obviate  any  putrefactive 
process,  and  that  if  this  could  be  obviated,  the  matter 
in  question  would  continue  fit  for  my  experiments,  so 
long  as  it  should  be  kept  secluded  from  light.  And  in 
these  respects  my  belief  appears  to  have  been  well 
founded,  since  even  now  (August,  1812,)  when  almost 
nine  years  have  elapsed,  I  find  that  the  bits  of  muslin 
so  shut  up,  (of  which  a  score  are  still  remaining)  ex- 
hibit only  the  yellowish  spots  given  by  this  matter  as 
when  first  applied  to  them,  and  that  they  are  as  capable 
as  ever,  of  passing  through  the  usual  changes  of  colour, 
and  finally  becoming  purple,  if  assisted  by  the  sun's 
rays.  They  do  this  indeed  more  slowly,  when  exposed 
without  being^r^^  moistened;  but  after  being  dipped  in 
water,  the  changes  succeed  as  regularly,  and  quickly, 
as  they  have  usually  done  with  matter  just  taken  from 
its  natural  receptacle,  and  the  experiments  which  I  am 


Philosophy  of  Permanent  Colours,  111 

now  about  to  relate,  were  all  made  with  the  matter 
which  had  been  so  applied,  either  to  muslin  or  calico, 
and  secluded  from  light,  more  than  seven  years. 

1st.  A  bit  of  calico,  so  impregnated  and  secluded 
from  light,  was  put  into  a  very  small  white  glass  phial,  , 
and  the  latter  being  filled  with  strong  nitric  acid,  which 
had  been  diluted  by  about  five  times  as  much  water,  it 
was  stopped  and  exposed  to  the  rays  of  the  summer's 
sun:  and  in  about  twice  the  usual  time,  as  nearly  as  I 
could  judge,  the  yellow  spots  became  first  greenish; 
then  of  an  apple  green,  and  afterwards  of  a  deep  grass 
green  colour:  but  here  the  progress  appeared  to  stop  so 
long,  that  I  began  to  think  it  would  proceed  no  farther: 
at  length,  however,  a  blue  tinge  became  evident,  then  a 
deep  blue,  and  finally  a  purple;  so  that  the  oxygene  of 
the  nitric  acid,  though  it  manifestly  retarded  the  usual 
changes,  did  not  hinder  their  ultimate  accomplishment. 
This  experiment  was  repeated,  with  a  substitution,  first 
of  diluted  sulphuric,  and  then  of  citric  acids,  instead  of 
the  nitric;  and  with  a  similar  obstruction  to  the  usual 
changes,  though  it  was  of  less  duration;  this  also  hap- 
pened with  the  acid  of  tartar.  A  similar  experiment 
being  made  with  undiluted  muriatic  acid,  the  several 
changes  terminating  in  a  fine  purple,  were  all  com- 
pleted, and,  as  I  thought,  in  little  more  than  half  the 
usual  time. 

This  experiment  was  repeated  with  bits  of  impreg- 
nated muslin,  by  substituting  caustic  solutions  of  pot- 
ash, soda,  and  ammonia  separately,  for  the  acids  before 
mentioned;  and  in  all  of  them,  the  purple  colour  was 
produced,  after  the  usual  changes,  in  full  perfection, 
and,  as  I  thought,  with  greater  celerity  than  they  had 
formerly  been  with  the  matter  just  extracted  from  the 
buccinum;  and  this  also  happened  with  muslin  immers- 
ed in  olive-oil. 


112  Philosophy  of  Permanent  Colours. 

A  similar  bit  of  muslin  put  into  a  phial  completely- 
filled  with  a  solution  of  tin,  in  muriatic  acid,  which  had 
been  recently  made,  and  was  at  the  minimum  of  oxida- 
tion (if  not  destitute  of  oxygene)  upon  being  exposed 
to  the  sun's  rays,  became  purple  with  great  celerity, 
after  passing  through  the  usual  succession  of  colours: 
and  this  was  the  case  with  another  bit  put  into  a  phial 
and  filled  with  the  oxymuriatic  acid  (chlorine  of  Davy) 
as  concentrated  as  any  which  I  could  procure.  This 
last  result  appeared  to  me  the  more  extraordinary,  be- 
cause I  had  previously  seen  this  acid  exert  its  destruc- 
tive influence  upon  the  purple  of  the  buccinum  pro- 
duced in  other  ways,  almost  as  quickly  and  efficaciously, 
as  it  is  known  to  do  upon  colouring  matters  generally: 
and  I  therefore  prolonged  this  experiment,  by  removing 
the  phial,  when  the  purple  was  completely  formed,  to  a 
siiration  where  the  direct  rays  of  the  sun  could  not 
reach  it;  and  there  I  found,  after  a  few  hours,  that  the 
very  same  acid  which  appeared  to  have  accelerated  the 
production  of  this  purple,  had  afterwards  annihilated 
the  colour  so  produced,  leaving  the  muslin  perfectly 
white! 

That  I  may  not  unnecessarily  prolong  this  account 
of  my  experiments,  I  will  omit  several  of  lesser  impor- 
tance, and  proceed  to  a  recital  of  two^  which  I  think 
conclusive,  in  regard  to  the  problematical  part  of  this 
inquiry,  viz. 

First, — into  a  flint  glass  phial,  more  than  half  filled 
with  quicksilver,  (strained  through  leather,)  I  conveyed 
a  triangular  bit  of  fine  muslin,  impregnated,  dried,  &c. 
as  before  mentioned;  and  having  attached  one  corner 
thereof,  by  compressing  it  between  the  glass  stopper, 
and  the  opposite  inner  surface  of  the  mouth  of  the 
phial,  I  inverted  the  latter,  so  that  the  quicksilver  sunk 
down  to  its  neck,  pushing  the  muslin  (which  by  this 


Philosophy  of  Permafient  Colours-  113 

attachment  was  hindered  from  ascending,  and  which 
had  been  previously  spread,)  closely  upon  one  side  of 
the  inner  surface  of  the  phial,  the  other  surface  being 
in  immediate  contact  with  the  quicksilver,  which  rose 
an  inch  above  the  muslin;  so  that  the  latter  was  com- 
pletely secured  from  the  access  of  atmospheric  air;  that 
which  the  phial  contained,  being  forced  by  the  superior 
weight  of  the  mercury  into  the  space  above  it.  Thus 
circumstanced,  the  phial  (in  the  month  of  August,) 
was  exposed  to  the  sun's  rays,  that  side  of  it,  upon  the 
inner  surface  of  which  the  muslin  was  applied,  being 
turned  towards  them:  and  in  this  situation  I  observed 
the  muslin,  or  raiher  the  colouring  matter  of  the  bucci- 
num,  to  pass  through  all  the  shades  of  green  and  blue, 
and  become  a  full  reddish  purple  with  as  much  celerity, 
as  similar  matter  in  a  dried  state,  hud  commonly  done, 
when  exposed  to  the  sun's  beams,  with  the  free  access 
of  atmospheric  air. 

Though  it  appeared  difficult  to  devise  any  experi- 
ment more  decisive  than  this,  I  made  a  second,  by  fil- 
ling with  quicksilver,  a  small  cylindrical  glass  tube,  34 
inches  long,  and  closed  at  one  end;  and  having  stopped 
the  orifice  with  my  finger,  I  inverted  the  glass  upon  a 
china  cup,  containing  more  quicksilver,  and  then,  with- 
drawing my  finger,  the  mercury  sunk,  and  left  a  va- 
cuum above  it,  of  about  four  inches  in  height:  I  then 
placed  a  bit  of  line  muslin  impregnated,  dried,  &c.  as 
before  mentioned,  under  and  immediately  before  the 
orifice  of  the  tube,  through  which  it  ascended  with 
great  rapidity  into  the  vacant  space,  and  being  then 
exposed  to  the  sun's  rays,  the  usual  changes,  termi- 
nating in  a  purple  colour,  all  took  place,  as  in  the  pre- 
ceding experiment,  and  wdth  equal  celerity. 

In  the  first  of  these  latter  experiments,  there  was  no 
vacuum,  but  the  muslin  with  its  colouring  matter,  was 

Vol.  I.  P 


1 1^  Philosophy  of  Permanent  Colours, 

in  close  and  immediate  contact  with  the  inner  surface  of 
the  glass,  and  with  the  quicksilver  in  every  other  part; 
so  that  nothing  else  could  possibly  reach  the  colouring 
matter,  excepting  the  light  passing  through  the  glass. 
In  the  second  experiment,  the  muslin  was  placed  in 
vacuo,  but  the  colouring  matter,  was  equally  protected 
by  the  glass  and  quicksilver  from  the  access  of  every 
thing  but  light.  In  both  experiments,  the  bits  of  muslin 
employed,  were  perfectly  dry,  and  the  quicksilver,  when 
brought  into  contact  with  them,  occasioned  no  change 
or  impression  whatever,  upon  the  colouring  matter,  not 
an  atom  of  it  adhering  thereto,  or  to  any  part  of  the  mus- 
lin. The  changes  of  colour  therefore  could  only  have 
been  occasioned  by  the  sun's  rays,  and  it  is  now  well 
known,  that  their  most  common  and  general  effect  upon 
colouring  matters  is,  that  of  separating  oxygene: — their 
other  effect,  of  promoting  a  combination  of  it,  could 
not  possibly  have  been  produced  in  these  experiments, 
where  no  oxygene  existed.  Wishing,  however,  to  obtain 
as  much  additional  evidence  as  possible,  concerning  the 
sort  of  action  exercised  by  the  sun's  rays,  in  producing 
the  changes  before  mentioned,  I  took  a  piece  of  muslin 
impregnated,  &.c.  as  in  the  former  experiments,  and 
having  wetted  it  with  water,  which  had  just  boiled  and 
was  partly  cooled,  I  spread  the  muslin  on  white  paper, 
in  a  place  accessible  to  the  sun's  rays,  and  separating 
the  latter  by  a  triangular  prism,  I  brought  the  solar 
spectrum  to  bear  completely  upon  the  colouring  matter 
of  the  buccinum,  and  was  soon  convinced  that  the  usual 
changes  of  colour  proceeded  faster  and  more  distinctly 
under  the  deoxygenating  rays,  at  the  violet  extremity, 
than  they  did  at  the  other  extremity  under  the  red  rays; 
the  muslin  becoming /7z/r/;/d'  at  the  former,  whilst  at  the 
latter  it  had  become  only  blue. 


Philosophy  of  Permanent  Colours.  115 

There  is,  moreover,  another  proof  of  the  separation 
of  oxygene,  when  the  purple  under  consideration  is 
produced,  and  it  is  connected  with  the  strong  disagree- 
able odour,  nearly  resenibling  that  of  ga?'llc^  which  was 
so  distinctly  perceived  by  Cole  and  Reaumur,  and  which 
has  constantly  assailed  my  nostrils,  whenever  the  colour- 
ing matter  of  the  buccinum  began  to  turn  green,  nnd 
has  continued  to  do  so,  without  diminution,  until  some 
time  after  the  purple  colour  was  fully  produced.  This 
odour  to  my  senses,  unequivocally  indicates  the  pre- 
sence of  phosphorus,  which  is  contained  in  all  animal 
substances;  and,  when  subjected  to  the  action  of  the 
sun's  rays,  readily  becomes  volatile  in  part,  by  com- 
bining with  a  portion  of  oxygene;  and  this  volatile 
part  or  compound  (which,  as  Davy  observes,  p.  287, 
**  should,  according  to  the  principles  of  the  French  no- 
menclature, be  C2i\\^d.  phosphorous  acicP'')  emits  an  offen- 
sive alliaceous  smell,  very  much  like  that  of  the  colour- 
ing matter  of  the  buccinum,  when  it  becomes  purple. 
The  last,  or  that  part  of  it  which  gives  the  smell  of 
garlic,  readily  mixes  with  water,  and  strongly  impreg- 
nates it  with  this  odour,  as  I  have,  found  by  many  ex- 
periments; and  in  this  respect  it  also  agrees  exactly 
with  the  volatile  compound  which  gives  the  alliaceous 
odour  from  phosphorus. 

I  repeated  Reaumur's  experiment  with  corrosive  sub- 
limate of  mercury,  and  found  that  the  purple  which  re- 
sulted, partook  more  of  the  blue  tint  than  usual,  and 
this  appeared  to  be  the  case  when  the  colouring  matter 
of  the  buccinum  was  mixed  with  sulphate  of  iron. 

Pliny,  as  my  readers  will  have  seen,  represents  the 
purple  colour  obtained  from  the  buccinum,  as  not  being 
permanent,  without  a  mixture  of  that  from  the  purpura; 
but  on  this  point  he  was  certainly  misinformed,  it  being 
of  itself  the  most  durable  of  all  animal  colours.  I  found 


116  Philosophy  of  Per 7nanent  Colours, 

that  it  was  not  sensibly  affected,  even  upon  fine  muslin, 
by  being  wetted  wixh  undiluted  oxy muriatic  acid,  though 
when  immercd  in  a  phial  filled  with  this  liquor,  it  soon 
disappeared,  as  I  believe  would  happen  to  almost  every 
other  animal  or  vegetable  colour.  I  found  also  that  un- 
diluted oil  of  vitriol  dropped  upon  a  bit  of  calico,  which 
had  been  made  purple  by  the  matter  of  the  buccinum, 
did  not  destroy  the  colour,  though  it  produced  a  tinge 
inclining  more  to  the  blue.  Highly  concentrated  and 
smoking  nitrous  acid,  applied  to  a  similar  bit  of  calico, 
changed  the  purple  to  a  yellow  colour,  which  became 
very  lively  and  beautiful,  upon  being  rinced  in  a  solu- 
tion of  potash.  ThiTiking  it  not  unlikely  that  this  change 
might  have  resulted  from  a  combination  of  oxygene, 
with  the  colouring  matter,  rather  than  from  an  irrepa- 
rable decompositio7i  of  it,  I  exposed  the  yellow  in  ques- 
tion to  the  direct  action  of  the  sun's  rays,  to  see  whether 
their  deoxygenating  power  would  reproduce  the  purple, 
but  no  such  effect  ensued;  the  yellow  remaining,  and 
seeming  to  be  permanent.  Strong  muriatic  acid  applied 
to  a  similar  bit  of  calico,  appeared  to  have  no  effect 
upon  the  purple  colour;  and  single  aquafortis  changed 
it  less  than  the  much  weaker  oxymuriatic  acid. — But 
I  will  proceed  no  fiirther  with  my  observations,  believr 
ing  that  I  have  now  sufficiently  explored  and  eluci- 
dated this  hitherto  abstruse  subject.  Some  of  my  rea- 
ders may  indeed  think  that  1  have  been  too  minute  in 
my  statements  concerning  it.  But  to  me,  the  colour- 
ing matter  under  consideration,  has  appeared  to  deserve 
my  utmost  attention,  because,  (independently  of  the 
veneration  with  which  it  was  contemplated  by  the  an- 
cients) its  properties  are  more  extraordinary,  more  in- 
teresting, and  more  instructive,  than  those  of  any  other. 
It  is  strictly  and  pre-eminently  intitled  to  the  distinction 
ot  a  substantive  colour,  as  it  may  be  permanently  fixed. 


Philosophy  of  Permmient  Colours.  117 

even  upon  linen  and  cotton,  by  the  most  simple  appli- 
cation, and  without  any  preparation  or  admixture  what- 
ever: and  it  is  admirable,  for  the  singular  constancy 
with  which  it  proceeds,  through  the  scries  of  interme- 
diate colours,  (according  to  their  prismatic  arrangement) 
until  it  has  permanently  fixed  itself  and  attained  that 
purple  tint,  which  the  Author  of  Nature,  for  some  un- 
known purpose,  has  fitted  it  to  display;  and  all  this,  in 
spite,  if  I  may  so  express  myself,  of  many  powerful 
chemical  agents,  whose  utmost  influence  extends  only 
to  retard,  for  a  few  hours,  the  ultimate  accomplishment 
of  this  its  destiny. 

The  celebrated  Fontenelle,  in  giving  (as  Secretary  of 
the  Royal  Academy  of  Sciences  at  Paris)  his  account 
of  Reaumur's  discovery,  began  by  observing,  that  not 
only  more  things  were  found  in  modern,  than  had  been 
lost  in  ancient  times,  but  that  it  was  even  impossible 
for  any  thing  to  be  lost  unless  mankind  were  willing  that 
it  should  remain  so;  it  being  only  necessary  to  search 
in  the  bosom  of  nature,  where  nothing  is  annihilated; 
and  that  to  be  certain  of  the  possibility  of  a  thing's 
being  found,  was  a  considerable  step  towards  finding  it. 
But  before  the  buccinum  and  purpura  were  found  by 
Cole,  Reaumur,  and  Duhamel,  America  had  been  dis- 
covered, and  new  dyeing  materials  thence  obtained, 
superior  in  beauty,  and  especially  in  cheapness,  to  those 
so  highly  valued  in  ancient  times;  though  it  must  be 
confessed  that  no  other  substance  will  afford  a  substan- 
tive purple  of  equal  beauty  and  durability,  and  capable 
of  being  topically  applied  to  linen  and  cotton  with  so 
much  simplicity  and  expedition;  and  for  these  reasons 
it  seems  probable  that  the  discoveries  of  these  gentle- 
men might  still  be  rendered  beneficial  in  staining  or 
printing  fine  muslins,  for  which  but  little  colouring 
matter  is  required.  And  indeed,  there  was  a  species  of 


1 18  Philosophy  of  Permanent  Colours. 

buccinum  found  more  than  a  century  ago  near  Panama, 
on  the  coasts  of  Guayaquil  and  Guatemala,  of  which  con- 
stant use  appears  to  have  been  made  in  those  countries, 
for  the  dyeing  or  staining  of  cotton,  as  Jussieu,  the 
elder,  Thomas  Gage,  and  others  have  mentioned.  Don 
Antonio  Ulloa,  in  particular,  says,  "  they  are  something 
larger  than  a  nut,  and  contain  a  juice  which,  when  ex- 
pressed, is  the  true  purple;  for  if  a  thread  of  cotton  or 
the  like  be  dipped  into  this  liquor,  it  becomes  of  a  most 
vivid  colour,  which  repeated  washings  are  so  far  from 
obliterating,  that  they  rather  improve  it;  nor  does  it  fade 
by  wearing."  "  This  precious  juice,"  continues  he,  "  is 
extracted  by  different  methods;  some  take  the  fish  out 
of  the  shell,  and  laying  it  on  the  back  of  the  hand,  press 
it  with  a  knife  from  head  to  tail,  separating  that  part  of 
the  body  into  which  the  compression  has  forced  the 
juice,  and  throw  away  the  rest."  This  being  done, 
*'  they  draw^  threads  through  the  liquor  which  is  the 
whole  process;  but  the  purple  tinge  does  not  appear 
immediately,  the  juice  being  at  first  of  a  milky  colour, 
from  which  it  changes  to  a  green,  and,  lastly,  to  this 
celebrated  purple."  See  the  translation  of  his  account 
of  the  voyage  to  South  America,  &c.  vol.  i.  p.  268-9. 

Snails,  with  the  same  property,  exist  in  various  other 
parts  of  the  world.  Catesby,  in  describing  the  Bahama 
islands,  (vol.  i.  p.  xliv.)  mentions  among  the  shells 
there,  the  *'  Buccinum  brevi  rostrum  muricatum,  ore 
ex  purpuro  nigricante  dentato,"  adding,  *'  these  shells 
stick  to  rocks  a  little  above  low  water,  and  are  conse- 
quently a  short  time  uncovered  by  the  sea.  They  yield 
a  purple  liquor,  like  that  of  the  murex,  which  will  not 
wash  out  of  linen  stained  with  it." 

Josselyn  also,  in  his  New  England  Rarities  discover- 
ed," p.  37,  says,  "  at  Paschataway,  a  plantation  about 
50  leagues  by  sea,  eastward  of  Boston,  in  a  small  cove, 


Philosophy  of  Permanent  Colours.  119 

called  Baker's  Cove,  they  found  this  kind  of  muscle, 
which  hath  a  purple  vein,  which  being  pricked  with  a 
needle,  yieldeth  a  perfect  purple  or  scarlet  juice,  dyeing 
linen  so  that  no  washing  will  wear  it  out,  but  keeps  its 
lustre  many  years:  we  mark  our  handkerchiefs  and 
shirts  with  it.  Mr.  John  Nieuhoff  moreover  relates,  that 
^^  abundance  of  purple  snails  are  found  in  the  islands 
over  against  Batavia."  "  They  are  boiled  (adds  he)  and 
eaten  by  the  Chinese,  who  have  a  way  of  polishing  the 
shells,  and  pick  out  of  the  middle  of  the  snail  a  certain 
purple-co\o\xr^d  substance*  which  they  use  in  colour- 
ing, and  in  making  red  ink." 

In  the  fiftieth  volume  of  the  Philosophical  Transac- 
tions, Dr.  J.  A.  Peysonnel,  F.  R.  S.  describes  what  he 
calls  the  naked  snail  producing  purple,  (*'  Limax  non 
cochleata,  purpur  ferens,")  as  being  found  in  the  seas 
of  the  Antilles,  and  "  precious  for  the  beautiful  purple 
colour  it  produces  in  the  same  manner  that  the  cuttle- 
fish produces  its  ink."  "  There  is  (continues  he)  a  hol- 
low in  the  back  of  the  animal,  v*^here  the  canal,  filled 
with  a  reddish  juice,  passes  out,  carrying  it  to  a  fringed 
body  like  a  mesentery;  and  it  is  there  the  purple  juice 
is  brought  to  perfection."  '*  When  the  animal  is  touch- 
ed, he  makes  himself  round  and  throws  out  his  purple 
juice  as  the  cuttle-fish  does  his  ink:  this  juice  is  of  a 
beautiful  deep  colour;  it  tinges  linen,  and  the  tincture 
is  difficult  to  get  out." 

It  is  however  to  be  remarked,  that  the  liquor  of  the 
naked  snail  exists  naturally  of  a  purple  colour,  without 


*  Probably  this  description  is  inaccurate,  for  if  the  substance  in 
question,  exhibits  a  purple  colour,  when  taken  immediately  fiom 
the  body  of  the  snail,  it  must  differ  in  its  nature  and  properties 
from  the  purple  of  either  the  murex  or  buccinum,  and  nearly  re- 
semble that  of  the  snails,  mentioned  in  the  succeedinij  paragraphs. 


120  Philosophy  of  Permanent  Colours, 

the  application  of  light;  a  circumstance  which  denotes 
very  diiFerent  properties  from  those  of  the  buccinum. 
In  Brown's  History  of  Jamaica,  there  are  descriptions 
of  two  shell-fishes  having  a  similar  colouring  liquor;  one 
is  termed  *'  the  larger  dark  lernea,  or  sea  snail,  frequent 
in  the  American  seas."  Dr.  Brown  observes,  that  **  on 
touching  this  creature,  it  emits  a  considerable  quantity 
of  viscid  purple  liquor,  which  thickens  and  colours  the 
\vater  about  it  so  much,  that  it  can  scarcely  be  seen  for 
some  time  after,  by  which  means  it  is  generally  enabled 
to  make  its  escape  in  times  of  danger."  *'  I  have  ga- 
thered," adds  Dr.  Brown,  "  a  small  quantity  of  the  dis- 
charges of  this  creature,  and  stained  a  linen  handker- 
chief with  it;  it  gives  a  very  beautiful  dark  purple  co- 
lour, which  is  not  apt  to  change  with  either  acids  or 
alkalies;  but  is  easily  washed  out:"  a  circumstance  in 
which  it  totally  diiFers  from  the  buccinum,  &c.  as  well 
as  in  that  of  the  liquor  being  naturally  emitted  of  a  pur- 
ple colour.  The  other,  of  these  shell-fishes,  is  termed 
cochlea  ima,  or  the  purple  ocean  shell;  and  upon  being 
touched,  "  it  diffuses  a  beautiful  purple  liquor,"  says 
Dr.  Brown,  which  seems  to  resemble  the  former.  The 
sepia,  or  cuttle-fish,  has  long  been  known  to  provide 
for  its  safety  in  like  manner,  by  discharging  in  times  of 
danger,  a  viscid  bitter  black  fluid,  which  Rondeletius 
mistook  for  bile,  and  which,  I  know  by  experiments,  to 
be  as  dissimilar  as  possible,  to  the  colouring  matter  of 
the  buccinum,  and  utterly  incapable  of  serving  any  use- 
ful purpose  in  dyeing;  and  I  am  persuaded,  this  must 
be  true  also,  of  the  liquor  of  Dr.  Brown's  shell-fishes, 
and  that  of  Dr.  Peysonnel's  naked  snail.  A  similar 
mistake  seems  to  have  been  committed  by  M.  Cuvier, 
one  of  the  latest,  most  respectable,  and  best-informed 
writers  upon  comparative  anatomy,  who  has  evidently- 
confounded  the  testacca,  affording  the  purple  of  the 


Philosophy  of  Permanent  Colours^  Igi  ■ 

ancients,  with  a  considerable  number  of  the  vermes 
of  Linnaeus,  (principally  moUuscae)  naturally  destined 
to  secrete,  and  when  in  danger  to  eject,  dark- coloured 
fluids,  that,  by  obscuring  the  water,  they  may  be  ena- 
bled to  escape;  a  purpose  totally  different  from  that  of 
any  fluid  secreted  by  the  murex  or  buccinum,  and  af- 
fording the  purple  of  the  ancients.  See  Cuvier's  Ana- 
tomic Comparee,  torn.  v.  263,  4. 

Mr.  Martin  Lister,  (see  Philosophical  Transactions, 
vol.  vi.)  observes,  that  "  the  common  hawthorn  caterpil- 
lar will  strike  a  purple,  or  carnation,  widi  ley,  and  stand; 
the  heads  of  beetles  and  pismires  will,  with  ley,  strike 
the  same  carnation  colour,  and  stand;  and  the  amber- 
coloured  scolopendra  (adds  he)  will  give,  with  ley,  ai 
most  beautiful  and  pleasant  amethystine,  and  stand:^*^ 
but  whether  he  means  that  they  will  stand  in  this  way, 
when  applied  to  paper  only,  or  to  the  substances  usually 
made  to  receive  dyes,  does  not  appear.  In  another  part 
of  the  same  volume,  Mr.  Lister  mentions  an  insect 
(cimex,)  whose  eggs,  bruised  upon  white  paper,  "  stain 
it  of  themselves,  without  any  addition  of  salt,  of  a  lively 
vermilion  colour." 


Vol.  L  Q 


122  Philosophy  of  Permanent  Colours, 


CHAPTER  V. 

Of  Vegetable  Substantive  Colours^  and  principally  of  In- 
digo, and  the  Plants  affording  it,  or  a  similar  Colour. 

"  Combien  de  tentatives  n'aura  t'on  pas  fait,  avant  que  de  parvenir  au  point  d'ap- 
pHquer  convenablement  les  eouleurs,  sur  les  etoffes,  et  de  Feurdonner  cette  adhe- 
rence et  ce  lustre,  qui  fait  le  principal  merite  de  Tart  du  teinturier,  un  des  plus 
agreables,  mais  en  merac  tenaps  un  des  plus  diflriciles  qu*on  connoisse!"  Goguet  dc 
VOrigine  des  Lois,  des  ^^ris,  et  des'  Sciences,  &c.  to  we  premier,  ito. 

The  subject  of  this  article  is  the  most  interesting, 
important,  and  instructive,  which  can  occupy  the  atten- 
tion of  a  dyer,  or  a  chemist;  the  admirable  and  singular 
properties  of  indigo  being  only  surpassed  by  those  of 
the  colouring  matter  of  the  murex  and  buccinum,  a 
little,  while  it  is  of  much  higher  practical  utility  than 
the  latter.  From  the  remotest  ages  of  which  we  have 
any  correct  information,  mankind  appear  to  have  pos- 
sessed and  employed  the  means  of  dyeing  or  staining 
blue  colours  substantively,  either  upon  their  skins  or 
clothing.  In  the  more  temperate  climates,  this  was  done 
from  the  plant  denominated  isatis,  by  Linnaeus,  as  well 
as  by  the  Greeks  and  Romans,  and  commonly  known 
in  this  country  by  the  name  of  woad:  but  in  warmer 
situations,  the  colour  in  question  was  chiefly  obtained 
from  some  of  the  indigoferas  (of  Linnaeus),  or  other 
vegetables  of  the  natural  order  of  Papilionacase,  or  that 
of  leguminosse.  The  plants  so  employed,  all  contained 
more  or  less  of  the  basis  of  indigo,  combined  with  but 
a  small  portion  of  oxygene,  and  therefore  capable  of 
being  extracted,  and  held  in  solution  by  water,  long 
enough  at  least  for  its  application  as  a  dye.  And  it  is 
not  therefore  surprising  that  the  inhabitants  of  all  coun- 
tries, excepting  India,  should  have  thought  it  sufficient 
to  pound  or  grind  the  plants  naturally  containing  this 


Philosophy  of  Permanent  Colours,  123 

basis;  and  after  a  partial  and  premature  fermentation,  in 
some  places,  to  dry  the  matter  so  pounded  or  ground; 
leaving  the  dyer,  when  necessary,  to  macerate  and  give 
it  an  additional,  or  other  sufficient  fermentation,  to  ena- 
ble the  basis  to  absorb  such  farther  portion  of  oxygene, 
as,  when  assisted  by  the  dyeing  process,  would  fix  it 
permanently  in  the  dyed  cloth,  and  fully  manifest  its 
blue  colour. 

This  partial  fermentation  of  the  bruised  plant,  pre- 
vious to  its  being  dwed,  was  chiefly  practised  in  regard 
to  the  woad  or  isatis,  of  which  two  species,  differing  but 
little  from  each  other,  are  cultivated  in  Europe,  viz.  I — 
Tinctoria,  and  I —  Lusitanica:^  with  the  indigo  plants 

*The  preparation  given  by  the  Greeks  and  Romans  to  the  isatis, 
js  not  I  believe  described  by  any  of  their  writers,  but  that  of  the 
moderns  is  well  known.  The  plant,  after  being  cut,  washed,  and 
partly  dried,  is  carried  to  a  mill,  and  there  ground  to  a  paste,  after 
which  it  is  formed  into  a  mass  or  heap,  and  being  covered  to  pro- 
tect it  from  rain,  is  left  to  undergo  a  partial  fermentation  for  about 
a  fortnight. — The  heap  is  then  stirred,  well  mixed,  and  formed 
into  balls  or  cakes,  which  are  exposed  to  the  sun  and  wind  to  dry, 
and  thereby  obviate  the  putrefactive  process,  which  would  other- 
wise take  place.  Being  afterwards  collected  in  heaps,  these  balls 
again  ferment,  become  hot,  and  emit  the  odour  of  ammonia  or  vo- 
latile alkali,  which,  as  Mr.  Hume  tells  us,  in  the  44th  chapter  of 
his  Histoiy,  gave  such  offence  to  Queen  Elizabeth,  that  she  issued 
an  edict  to  prohibit  the  cultivation  of  this  plant:  had  she  prohibited 
the  making  it  to  ferment,  except  by  the  dyer,  she  would  have  acted 
more  wisely.  After  the  heat  has  continued  for  some  time,  these 
balls  fall  into  a  dry  powder,  and  are  then  sold  to  the  dyer,  who  now 
seldom  employs  them  without  a  mixture  of  indigo,  which  last  the 
woad  helps  to  deoxygenate  and  render  soluble.  Formerly,  however, 
this  preparation,  fermented  by  well-known  means,  was  employed 
rt/one,  though  it  was  incapable  of  giving  a  deep  and  bright  blue 
colour,  because  the  tingent  matter  was  in  union  with  too  great  a 
proportion  of  the  other  constituent  matters  of  tlic  plant.  The  co- 
lour, however,  which  it  did  give,  was  very  durable.  But  the  best 
methods  of  cenducting  the  fermentation  and  preparation  of  woad 


124  Philosophy  of  Permanent  Colours, 

this  sort  of  fermentation  seems  not  to  have  been  thought 
necessary,*  by  a  great  part  of  mankind. 

are,  even  at  this  time,  so  little  understood,  by  the  persons  exercis- 
ing that  employment,  that  the  goodness  of  any  parcel  of  it  can 
never  be  ascertained,  otherwise  than  by  the  actual  use  which  dyers 
afterwards  make  of  it,  and  this  commodity  is  therefore  purchased 
under  the  greatest  uncertainty  respecting  its  true  value,  and  it 
would  therefore  be  better  to  dry  and  sell  it  unfermented.  It  has 
lately  suited  the  policy  of  the  French  government,  to  cause  the 
isatis  to  be  cultivated  for  the  purpose  of  obtaining  indigo  from  it, 
by  a  process  analogous  td  that  employed  in  the  East  and  West 
Indies,  with  the  indigofera  tinctoria,  and  I  have  seen  some  of  the 
indigo  so  produced,  but  I  do  not  think  that  in  goodness  and  cheap- 
ness it' can  ever  rival  that  from  the  indigo  plants,  which  at  the  pro- 
per age  will  afford  nearly  thirty  times  as  much  indigo,  as  an  equal 
weight  of  the  isatis  tinctoria> 

*  Francois  Cauche,  after  describing  the  indigo  plant  at  Mada- 
gascar, says  the  natives,  "  pillent  les  feuilles  avec  leur  branches, 
etant  encore  tendres,  et  en  sont  des  pains,  chacun  de  la  pesanteur 
de  trois  livres,  qu'ils  font  secher  au  soleil;  s*ils  veulent  teindre,  ils 
en  piilent  un,  ou  deux,  ou  trois,  suivant  qu'ils  en  ont  besoin,  ct 
mettent  la  poudre  dans  des  pots  de  terre,  qu'ils  font  bouillir  avec 
de  I'eau  sur  le  feu  puis  tirent  leurs  pots,  laissant  refroidir  ce  qui 
est  dedans,  y  trempant  leur  cotton  et  leur  soye."  Voyage  de  Fran- 
cois Cauche,  en  Tisle  de  Madagascar,  &c.  4to.  Paris  1651.  p.  151. 
M.  Adanson  gives  a  similar  account  of  the  method  of  using  the  in- 
digo plant  by  the  natives  of  Senegal,  except  that  he  mentions,  as 
perhaps  Cauche  ought  to  have  done,  that  a  ley  of  vegetable  ashes 
is  employed  in  dyeing  with  it.  See  his  voyage,  &c.  Capt.  George 
Roberts  also,  in  the  account  of  his  four  years'  voyages,  mentions 
the  indigo  plant  as  growing  wild  at  Bonavista,  one  of  the  Cape  de 
Vcrd  islands;  and  that  the  natives  prepare  it,  "  only  by  pounding 
the  leaves  of  the  shrub  while  green,  in  a  wooden  mortar,  with  a 
wooden  pestle,  and  so  reduce  it  to  a  kind  of  pap,  which  they  form 
into  thick  round  cakes,  or  balls,  and  drying  it,  keep  it  till  they  have 
occasion  to  use  it  for  dyeing  their  clothes." — He  observes  "  that 
the  cakes  in  drying,  change  from  a  green  to  a  blue  colour,  (proba- 
bly by  absorbing  oxygene)  and  that  the  natives  extract  the  dye  by 
means  of  a  lixivium,"  as  I  suppose,  of  wood  ashes.  Mr.  Mungo 
i*ark,  in  the  account  of  his  travels  in  Africa,  says,  that  to  dye  cloth 


Philosophy  of  Permanent  Colours »  125 

By  what  circumstance  or  event  the  people  of  Hindos- 
tan  alone  were  led,  several  thousand  years  ago,  to  dis- 
cover and  adopt  means  by  which  the  blue  colourable 
matter  of  the  indigo  plant  might  be  extracted,  oxygen- 
ated, and  precipitated,  free  from  almost  all  the  other 
matters  naturally  combined  with  it,  and  afterwards 
brought  into  the  dry  solid  form  in  which  we  now  find 
it,  no  one  can  I  believe  conjecture.  But,  as  an  accurate 
knowledge  of  the  process  by  which  all  this  can  best  be 
effected,  will  greatly  conduce  to  a  right  understanding 
of  the  nature  and  constitution  of  this  wonderful,  and 
most  valuable  production,  1  shall  endeavour  to  give  the 
best  possible  account  and  explanation  of  it,  availing 
myself  of  every  thing  which  has  been  done  by  others, 
as  well  as  by  myself. 

of  a  lasting  blue  colour,  according  to  the  practice  of  the  negro 
women,  "  the  leaves  of  the  indigo  when  fresh  gathered,  are  pounded 
in  a  wooden  mortar,  and  mixed  in  a  large  earthen  jar,  with  a  strong 
ley  of  wood  ashes,  (chamber-ley  being  sometimes  added)  and  the 
cloth  is  steeped  in  this  mixture,  and  allowed  to  remain  until  it  has 
acquired  a  proper  shade." — ^*  When  indigo  is  most  plentiful;  they 
collect  the  leaves,  and  dry  them  in  the  aun^  and  when  they  wish  to 
use  them,  they  reduce  a  sufficient  quantity  to  powder,  and  mix  it 
with  ley  as  before  mentioned."  Vol.  i.  p.  97. 

Mr.  Marsden,  in  his  History  of  Sumatra,  p.  78,  says,  "  the  indigo 
shrub  (Taroom)  is  always  found  in  their  plantations,  but  the  natives 
to  dye  with  it,  leave  the  stalks  and  branches  for  some  days  in  water 
to  soak,  then  boil  it,  and  with  their  hands,  work  some  chunam 
(quicklime)  among  it,  with  the  leaves  of  the  pacoo  sabba  (a  species 
of  fern)  for  fixing  the  colour.  They  then  drain  it  off,  and  use  it  in 
a  liquid  state." 

To  conclude  this  note,  I  shall  only  add  the  following  extract  from 
Mr.  Barrow's  Travels  in  China,  p.  560,  "  Near  most  of  the  planta- 
tions of  cotton  we  observed  patches  of  the  indigo;  a  plant  which 
grows  freely  in  all  the  middle  and  southern  provinces.  The  dye 
of  this  shrub,  being  no  article  of  commerce  in  Chttia^  is  seldom  if 
ever  prepared  in  a  dry  state^  but  is  generally  unade  to  communi- 
cate its  colouring  matter /ro???  the  leaves.** 


126  Philosophy  of  Permanent  Colours, 

It  has  been  already  stated,  and  will  hereafter  be  abun- 
dantly proved,  that  indigo  principally,  and  essentially^ 
consists  of  a  peculiar  colourable  matter,  which  I  call 
its  basis,  and  which  being  combined  with  a  certain  por- 
tion of  oxygene,  is,  while  this  combination  subsists, 
thereby  rendered  insoluble  by  any  means  yet  known, 
excepting  those  which  exert  an  agency,  more  or  less 
destructive  upon  the  basis  itself.  This  basis  is  colourless 
when  destitute  of  oxygene,  and  seems  to  be  formed  by 
certain  peculiar  secretory  organs,  bestowed  upon  a  few 
particular  plants,  some  of  which  have  been  already  no- 
ticed, and  others  will  be  mentioned  hereafter:  but  though 
it  manifests  a  strong  affinity  for  oxygene,  when  separated 
from  the  different  matters  with  which  it  is  mixed  in  the 
plant,  the  basis  is  naturally  combined  with  so  little  of 
it,  as  to  be  liable  to  decomposition  and  injury  from  va- 
rious causes,  which  would  have  no  such  effect  upon  it, 
when  sufficiently  oxygenated,  as  it  is  in  the  state  of  in- 
digo. I  have  observed  repeatedly,  by  gathering  the  fresh 
leaves  of  the  indigo  plant,  inclosing  them  in  a  piece  of 
white  calico,  and  pressing  the  latter  strongly  upon  the 
leaves,  so  as  to  make  it  imbibe  their  juice,  that  a  green- 
ish tinge  was  first  produced  on  the  calico,  which  in  dry- 
ing,  approached  to  the  blue,  and  ultimately  assumed 
that  colour;  though  it  was  very  pale,  because  the  pro- 
portion of  colouring  matter,  or  rather  of  its  basis,  na- 
turally dispersed  through  the  juice  of  the  plant,  was  too 
small  to  produce  any  other  than  a  feeble  colour — it  was 
however  so  completely  fixed,  that  repeated  washings 
with  soap,  had  only  the  effect  of  rendering  it  brighter 
by  removing  the  other  matters  contained  in  the  juice  of 
the  plant,  and  applied  to  the  calico  with  the  blue  colour- 
ing matter.  By  repeating  these  applications  (of  the  juice 
of  the  leaves  in  question)  to  the  sa?ne  piece  of  calico 
several  times,  I  found  that  an  addition  of  blue  colour 


Philosophy  of  Permanent  Colours,  127 

was  made  by  each,  and  as  the  colour. so  communicated 
was  permanently  fixed,  I  have  concluded  that  in  regard 
to  the  degree  of  its  oxydation,  the  basis  of  indigo  so 
applied,  was  nearly  in  the  state,  in  which  it  commonly 
is,  in  the  composition  to  be  hereafter  described,  which 
the  calico  printers  apply  by  the  pencil,  to  give  perma- 
nent blue  stains,  or  figures.  I  suspect,  however,  that 
the  basis  of  indigo,  when  thus  applied  to  calico,  in  union 
with  the  unfermented  juice,  does  not  afterwards  oxy- 
genate itself  so  perfectly,  as  it  does  when  made  into 
indigo,  by  the  process  about  to  be  described.  The  juice 
expressed  from  the  bruised  leaves  of  the  indigo  plant, 
and  exposed  with  a  wide  surface  to  the  rays  of  the  sun, 
between  the  tropics,  and  thus  evaporated  to  dryness, 
before  any  fermentation  had  taken  place,  acquired  only 
a  greenish  blue  colour;  partly,  as  I  think,  because  the 
basis  of  the  indigo  was  but  imperfectly  oxygenated,  and 
partly  because  it  continued  to  be  mixed  with  a  yellow 
extractive  matter,  and  a  greenish  resin,  which  are  both 
iiaturally  contained  in  the  indigo  plant,  as  M.  Chevreul 
has  ascertained;  (see  Ann.  de  Chimie,  torn.  68.)  though, 
by  the  common  process  of  fermentation,  and  precipita- 
tion, the  indigo  is  in  a  great  degree  separated  from  them, 
as  well  as  from  the  other  matters  contained  in  its  juice. 
It  would  be  a  deviation  from  my  subject,  were  I  to 
give  any  account  of  the  cultivation  of  the  indigo  plant: 
I  may,  however,  be  permitted  to  observe,  that  the  spe- 
cies of  the  genus  indigofera,  most  frequently  employed, 
are  first, — Indigofera  anil,  a  large  hardy  plant  growing 
wild  in  the  hotter  parts  of  America,  and  affording  indigo 
of  good  quality. — 

2.  I —  Tinctoria;  which,  according  to  Loureiro, 
grows  spontaneously,  as  well  as  by  cultivation,  in  China, 
Cochinchina,  Hindostan,  Coromandel,  and  other  parts 
of  India,  whence  it  was  carried  to  America.  It  is  called 


128  Philosophy  of  Permanent  Colours. 

indigo  franc,  by  the  French,  and  is  less  hardy,  though 
more  productive  than  the  other  species. 

3.  I —  Disperina;  this  I  consider  as  the  species  called 
guatamala  indigo,  which  yields  a  line  pulp,  but  is  less 
productive  than  the  preceding;  and 

4.  I —  Argentea.  This  is  called  indigo  batard,  by 
the  French;  and,  as  Linnaeus  says,  was  also  a  native  of 
the  East  Indies.  All  these  are  suffruticose  plants,  or 
under  shrubs;  and  they  all  have  a  peculiar  smell,  which 
is  offensive  to  cattle. 

The  stems,  with  their  leaves  being  cut,  (which  is  best 
done  when  the  plant  is  in  full  blossom,)  are  placed  in 
large  vats,  called  sleepers^  and  pressed  down  by  planks 
and  wedges:  in  some  places  this  is  done  immediately 
after  being  cut;  in  others,  after  being  more  or  less 
dried;*  an  operation  which  probably  facilitates  the  so- 
lution and  extraction  of  the  indigo  basis;  as  the  falling 
of  rain  upon  hay^  is  found  to  deprive  it  of  a  greater  por- 
tion of  its  nutritious  parts,  than  grass  recently  mowed, 
would  have  lost  by  the  same  means.  Being  properly 
placed  in  vats,  the  leaves  and  twigs  are  covered  with 
water;  which  has  hitherto  been  most  frequently  em- 
ployed cold;  and  when  this  is  done,  the  appearances 
which  follow,  are  thus  described  by  Dr.  Roxburgh.! 

*  In  a  MS.  relating  to  the  manufacture  of  indigo,  belonging  to 
Sir  Hans  Sloane's  collection,  in  the  British  Museum,  (No.  4020, 
of  Ayscough*s  catalogue)  I  find  it  asserted,  that  in  some  parts  of 
the  East  Indies,  they  collect  the  leaves  of  the  indigo  plant  into  great 
heaps,  and  leave  them  to  grow  hot  and  sweat,  before  they  are 
steeped.  In  Egypt  they  grind  the  plant,  after  it  has  been  soaked 
an  hour  in  water  of  the  temperature  of  70*^  of  Reaumur,  or  190». 
of  Fahrenheit,  by  which  the  extraction  of  the  indigo  basis  is  facili- 
tated, but  the  broken  parts  of  the  plant  afterwards  become  mixed 
with  the  indigo,  and  render  it  impure. 

t  A&  a  supplement  to  the  former  edition  of  this  volume,  I  was 
induced  to  publish  (with  some  observations  of  my  own)  an  abstract 


Philosophy  of  Permanent  Colours.  129 

"  In  a  few  hours,  more  or  less,  according  to  circum- 
stances, a  slight  motion  begins  to  pervade  the  body  of 
the  liquor  in  the  vat;  the  bulk  increases  considerably, 
with  some  additional  heat;  air  bubbles  are  generated, 
some  of  which  remain  on  the  surface:  these  gradually 
collect  into  patches  of  froth;  a  thin  violet,  or  copper- 
coloured  pellicle,  or  cream,  makes  its  appearance  be- 
tween the  patches  of  froth;  soon  after,  the  thin  film 
which  forms  the  covering  of  the  bubbles  that  compose 
the  froth,  begins  ta  be  deeply  tinged  with  fine  blue. 
The  liquor  has  froni  the  beginning  been  acquiring  a 
green  colour,  and  now  it  will  appear,  when  viewed  fall- 
ing from  one  vessel  into  another,  of  a  bright  yellowish 
greetii  and  will  readily  pass  the  closest  filter,  until  the 
action  of  the  air  makes  it  turbid;  a  proof  that  the  base 
of  the  colour  is  now  perfectly  dissolved  in  the  watery 
menstruum:  this  is  the  time  for  letting  off*  the  vat.  If  suf- 
fered to  remain,  the  bulk  begins  to  diminish,  and  returns 

of  a  MS.  which  had  been  put  into  my  hands  at  the  East  India 
House,  containing  an  "  account  of  a  new  species  of  nerium,  tlie 
leaves  of  which  yield  indigo,"  &c.;  with  a  second  part,  containing 
*'  the  result  of  various  exfieriments  made  ivith  a  view  to  throiv  some 
light  on  the  theory  of  that  beautiful  production:  and  an  appendix 
containing  a  botanical  description  of  a  second  new  indigo  plant;  the 
whole  illustrated  with  drawings,  and  addressed  to  the  Honourable 
Sir  Charles  Oakley,  governor,  and  president  in  council  at  Fort  St. 
George,  to  be  transmitted  to  the  Court  of  Directors  of  the  United 
East  India  Company,  and  committed  to  their  protection,"  &c.  By 
William  Roxburgh,  M.  D.  But  as  the  whole  of  that  MS.  with  some 
few  additions  and  explanatory  engravings,  has  been  lately,  (and  in 
some  degree  upon  my  suggestion)  printed  as  a  part  of  the  28th 
volume  of  the  Transactions  of  the  Society  of  Arts,  Manufactures, 
and  Commerce,  I  am  enabled  to  abstain  from  a  republication  of  my 
former  abstract,  though  I  shall,  at  the  proper  places,  avail  myself 
of  the  most  interesting  of  Dr.  Roxburgh's  facts;  taking  them  from 
this  last  mentioned  volume  of  the  Society  of  Arts,  8cc.  to  which  my 
references  will  be  made. 

Vol.  L  R 


130  Philosophy  of  Permanent  Colours. 

to  its  original  dimensions;  however,  the  fermentation  con- 
tinues; there  is  still  much  intestine  motion  through  the 
vat,  and  large  quantities  of  froth  are  formed.  Hitherto  the 
peculiar  smell  of  the  plant  has  prevailed,  but  now  it  be- 
comes very  offensive,  something  like  that  of  animal  mat- 
ter beginning  to  putrefy.  As  fermentation  goes  on,  the 
smell  becomes  more  and  more  offensive,  and  the  quantity 
of  airs  discharged  less  and  less,  until  absorption  takes 
place." 

This  first  macerating  and  fermenting  process^  occa- 
sions an  extraction  of  the  indigo  basis,  and  an  imperfect 
oxygenation  of  it:  but  in  other  respects  I  do  not  know- 
that  it  is  of  any  importance,  to  the  production  of  indigo. 
Other  plants,  in  similar  circumstances,  would  ferment 
with  an  evolution  of  carbonic  acid  gas;  and  doubtless 
the  various  extractive  matters  of  the  indigo  plant,  par- 
ticipate and  co-operate  in  producing  the  appearances 
just  described  by  Dr.  Roxburgh;  who  has,  however, 
ascertained  that  in  the  first  part  of  this  process,  there 
was  a  great  absorption  of,  or  from  the  atmosphere,  (the 
free  access  of  which  was  indispensably  necessary  to  the 
fermentation),  and  this  absorption  doubtless  consisted 
principally  of  oxygene.  He  found,  moreover,  that  as 
soon  as  the  bulk  of  the  mass  began  to  be  enlarged,  a 
disengagement  of  airs  took  place,  which  he  describes  as 
being  ^^  fixed,  pure,  and  impure,"  (meaning,  I  presume, 
carbonic  acid  gas,  oxygene,  and  perhaps  hydrogene.)^ 
"  But,  continues  he,  about  the  time  that  the  bulk  of  the 
vat  is  greatest,  the  fixed  air  is  discharged  purer,  and  in 
larger  quantities  than  at  any  prior  period."  **  I  tried," 
he  adds,  *'  every  means  I  could  invent,  to  detect  the 
volatile  alkali,  that  I  was  led  to  expect,  but  without  the 
smallest  appearance  of  success,  at  any  time."  If,  as  soon 
as  the  fermenting  liquor  becomes  green,  an  alkali  be 
added  to  it,  a  precipitation,  says  M,  Dutrone,  will  take 
place,  "  d'une  fecule  verte  extremement  belle;"  and  at  a 


Philosophy  of  Permanent  Colours,  131 

ii'iore  advanced  state  of  the  process,  which  he  calls  "  la 
fermentation  putride,"  alkalies,  according  to  his  account, 
will  precipitate  a  ''feculequi  porte  une  couleur  bleu  de 
ciel  tres  legere." 

The  fermentation  being  completed,  the  green  colour- 
ed liquor  is  drawn  off,  from  the  steeper,  into  the  beating 
vat,  or  receptacle,  (which  the  French  call  batterie,) 
where  it  is  violently  agitated,  commonly  by  machinery, 
during  one,  two,  or  three  hours,  according  to  the  means 
adopted,  and  the  force  with  which  they  are  employed;  the 
effect  of  this  agitation  is  analogous  to  that  of  churning, 
for  by  promoting  a  farther  oxygenation  of  the  basis  of 
indigo,  it  renders  the  latter  insoluble,  in  the  liquor,  which 
had  previously  held  it  dissolved;  and  thereby  causes  it 
to  granulate,  or  collect  into  small  particles,  or  little 
flocula^,  suspended,  but  not  dissolved,  in  the  aqueous 
menstruum  which  still  retains,  in  solution,  the  other  mat- 
ters extracted  from  the  indigo  plant,  and  by  so  retaining 
them,  enables  the  manufacturer  to  separate  the  former 
from  the  latter,  by  adding  lime  water,  or  some  other 
suitable  precipitant,  which  is  to  be  mixed  with  the  li- 
quor, as  soon  as  a  distinct  granulation  becomes  manifest.  ^ 

*  Dr.  Roxburgh  has  believed,  that  the  basis  of  indigo,  during  the 
fermenting  process,  was  held  in  solution  by  carbonic  acid,  and  that 
agitation  and  precipitants  were  afterwards  useful,  the  former  by 
extricating  this  acid,  and  the  latter  by  absorbing  it.  That  such  ef- 
fects are  produced,  may  be  presumed  by  the  discharge  of  carbonic 
acid  gas,  which  is  manifest  during  the  agitation  of  the  liquor,  and 
by  the  cessation  of  that  discharge,  when  either  lime  water,  or 
caustic  alkali  is  added.  But  that  this  agitation  answers  another,  and 
more  important  end,  may  be  proved  even  from  some  of  Dr.  Rox- 
burgh's experiments  to  be  presently  noticed;  and  that  lime  water 
may  act  as  a  firecifiitant,  otherwise  than  by  absorbing  carbonic  acid, 
is  certain,  from  its  well  known  power  of  throwing  down  many  co- 
louring matters,  when  they  are  held  in  solution,  where  no  carbo- 
nic, or  other  acid  is  present;  in  such  cases  the  lime  acts  by  its  par- 
ticular affinity  for  these  colouring  matters,  in  the  same  way  in 


132  Philosophy  of  Permanent  Colours, 

During  this  last  agitating,  or  oxygenating  process, 
"  fixed  air,  (says  Dr.  Roxburgh,)  continues  to  be  dis- 
charged, with  pure  and  impure  airs;  but  still  nothing 
like  volatile  alkali."  But  when  the  precipitant  is  added, 
*'from  that  instant  an  absorption  of  air  takes  place;  and 
after  the  liquor  has  settled  a  little,  a  candle  will  burn 
freely  close  to  its  surface." 

The  most  efficacious  precipitants  hitherto  employed 
are  pure  well- burnt  lime  water,  and  the  different  alka- 
lies, especially  when  in  their  caustic  state;*  and  some  of 

which,  as  Dr.  Roxburgh  observes,  "  a  solution  of  tin  in  aqua  regia 
(in  a  very  small  proportion)  gives  a  Iai*ge  produce  of  light  blue  pre- 
cipitate,'* when  added  to  the  liquor  in  question.  Alum  acts  in  the 
same  way,  but  by  throwing  down  at  the  same  time  the  other  extrac- 
tive matters  of  the  plant,  it  debases  the  quality  of  the  indigo. 

*  Concerning  the  expediency  of  /irecipitantSy  Dr.  Roxburgh  de- 
livers the  following  opinion:  "  The  coloured  liquor,  impregnated 
%vith  the  first  principles  of  the  drug,  (its  base)  whether  acquired  by 
fermentation,  or  by  a  scaldhig  heat,  will,  without  the  least  of  our 
assistance,  if  only  exposed  to  the  open  air,  and  particularly  if  with 
a  large  surface,  in  a  short  time  begin  to  part  with  its  colour,  which 
will  fall  to  the  bottom  in  minute  grains  of  fine  blue  indigo:  agitation 
will  hasten  the  separation  and  precipitation  muc/if  and  cause  the 
produce  to  be  larger.  Heat  has  nearly  the  same  effect,  though  in 
a  less  degree,  except  when  joined  with  agitation,  in  which  case 
the  two  act  more  powerfully  than  either  alone.  The  indigo  procu- 
red by  these  means  is  good,  if  the  process  has  been  properly  con- 
ducted; precipitants  are  not  therefore  absolutely  necessary  for  the 
production  of  indigo,  but  if  well  chosen,  and  in  a  proper  proportion, 
they  forward  the  operation  muchy  causing  a  larger  produce  than 
could  be  had  without  them;  and  I  have  reason,  from  a  variety  of 
experiments,  to  say,  that  the  quality  is  by  no  means  injured  in  con- 
sequence."— Dr.  Roxburgh  thinks  lime  water  preferable  to  any 
other  precipitant;  alkalies,  he  says,  "answer  the  best  when  made 
caustic,  but  even  then  lime  water  gives  a  purer  indigo,  though 
probably  not  in  quite  so  greata  quantity."  He  adds  that  "  if  lye  per- 
fectly caustic  be  added,  before  the  liquor  has  been  agitated,  or  be- 
fore any  granulation  has  taken  place,  the  extractive  matters  of  the 
plant  will  generally  be  precipitated  first,  in  the  form  of  a  dirty  pale 
yellow  fecula:  in  the  mean  time  the  supernatant  liquor  gradually 


Philosophy  of  Permanent  Colours,  133 

these  in  suitable  proportion  being  well  mixed,  and  the 
liquor  left  at  rest  for  six  or  eight  hours,  the  blue-colour- 
ed matter  will  commonly  be  found  to  have  all  subsided 
to  the  bottom,  leaving  the  supernatant  liquor  of  a  clear 
brandy,  or  Madeira  wine  colour:  when  it  appears  more 
or  less  green,  or  olive-coloured,  we  may  conclude  the 
separation  and  precipitation  of  the  indigo  have  been  but 
imperfectly  performed:  this  happens  indeed  but  too  of- 
ten, and  Dr.  Roxburgh  conceives  "  it  to  be  owing  to 
the  presence  of  fixed  air,  (carbonic  acid  gas)  still  adher- 
ing to,  and  keeping  dissolved  a  portion  of  the  base"  of  in- 
digo. I  think  it  more  probable,  however,  that  a  part  of 
the  basis  of  the  indigo  is,  in  such  cases,  hindered  by  the 
presence  of  carbonic  acid,  from  attracting  and  uniting 
to  itself  a  sufficient  portion  of  oxygene  to  cause  a  sepa- 
ration of  it  by  precipitation  from  the  other  extractive 
matters  yielded  by  the  plant;  it  having  been  found,  that 
by  renewing  the  agitation,  of  such  green  or  olive- colour- 
ed liquor,  and  adding  precipitants  to  it  afterwards,  more 
indigo  may  be  obtained.* 

acquires  from  the  surface  a  deep  blue  colour,  soon  becoming  turbid, 
and  lastly  the  blue  precipitate  of  real  indigo  will  be  formed  over 
the  first."  P.  281,  et  seq.  Precipitants,  therefore,  should  not  be 
added  to  the  liquor  until  the  indigo  basis  has  been  sufficiently  oxy- 
genated; which,  among  other  appearances,  may  be  known  by  a 
change  in  the  colour  of  the  froth  on  its  surface,  which,  after  ap- 
pearing blue^  becomes  colourless,  because  the  blue  matter  which 
gave  it  that  appearance  being  no  longer  dissolved,  subsides  from 
the  froth. 

*  As  the  profit  of  the  indigo  maker  greatly  depends  upon  his 
knowing  when  to  stop  the  fermenting,  as  well  as  to  the  agitating, 
process,  it  may  be  proper  that  I  should  subjoin  a  few  observations 
upon  each. 

The  fermentation  begins  soonest  when  the  weather  is  hottest,  and 
when  the  vat  has  been  recently  employed  for  the  same  purpose;  as 
it  then  retains  a  kind  of  fermenting  leaven.  If  the  fermentation  be 


134  Fliilosopliy  of  Permanent  Colours. 

Dr.  Roxburgh  ascertained  by  experiments,  which  are 
minutely  described  at  pages  278 — 281,  of  the  vokimc 
before  mentioned,  that  some  of  the  green  indigo  liquor, 
taken  when  just  fit  to  be  drawn  off  from  the  fermenting 

btopped  too  soon,  a  considerable  pait  of  the  colourable  basis  will  be 
left  unextracted,  and  lost  in  the  plant:  to  avoid  this  loss,  handfuls  of 
the  twigs  and  leaves  are  frequently  drawn  from  the  vat,  that  it  may 
be  ascertained  whether  they  are  become  of  a/ia/c  yellow^  and  the 
young  tops  made  tender.  Regard  should  also  be  had  to  the  colour 
of  the  liquor,  which,  so  long  as  the  fermentation  has  been  deficient, 
will  have  only  attained  a  yellowish  green,  with  a  copious  greenish 
IVoth,  capable  of  being  easily  dispersed  by  a  few  drops  of  oil,  which 
is  not  the  case  when  the  fermentation  ha£  been  carried  too  far.  In 
this  last  event,  the  froth  or  scum  generally  subsides,  and  the  green 
colour  of  the  liquor  will  lose  its  brightness,  appear  brownish  on  the 
surface,  and  become  turbid,  from  an  excessive  dissolution  and  ex- 
traction of  the  various  matters  belonging  to  the  plant.  The  liquor 
which  has  suffered  in  this  way,  cannot  bear  much  agitation  after- 
wards, without  farther  injury  to  the  indigo  resulting  from  it;  which 
will  become  either  blackish  or  of  a  dull  slate  colour,  and  be  found 
very  little  susceptible  of  either  granulation  or  precipitation;  and 
even  with  moderate  agitation,  the  liquor  which  has  undergone  this 
excessive  fermentation  will  never  afford  good  indigo.  But  where  the 
fermentation  has,  on  the  contrary,  been  deficient^  though  the  quantity 
ef  indigo  to  be  obtained  will  be  small,  the  quality  maybe  improved  by 
a  greater  degree  of  agitation.  When  too  little  of  this  last  is  given 
to  liquor  which  has  not  been  fermented  sufBciently,  the  indigo  will 
manifest  a  coarse  grain,  and  not  only  prove  less  in  quantity,  but  its 
blue  colour,  instead  of  the  coppery  gloss,  will  retain  a  greenish  cast. 
I  will  here  add,  in  regard  to  the  precipitants,  that  the  Javanese,  as 
M.  de  Cossigny  relates,  avoid  the  want,  and  use  of  them,  by  first  fer- 
menting the  indigo  plants,  and  then  boiling  the  liquor  for  a  little 
lime  before  it  is  agitated.  It  is  not,  I  believe,  the  practice  to  put 
water  a  second  time  upon  the  indigo  plants  in  the  fermenting  vat, 
in  order  to  extract  or  wash  out  any  remnant  of  the  indigo  basis,  left 
in,  or  adhering  to  the  plant,  after  the  fermented  liquor  has  been 
drawn  off;  but  I  am  persuaded,  that  if  this  were  done,  and  this 
washing,  or  second  extract,  were  added  to  the  first,  a  considerable 
portion  of  indigo  might  be  obtained,  which  I  believe  to  have  been 
hitherto  lost. 


Philosophy  of  Permanent  Colours.  135 

into  the  agitating  vat,  and  impregnated  with  carbonic 
acid  gas,  (in  Dr.  Nooth's  apparatus,)  would  afford  no 
granulation  or  precipitation  of  indigo.  This  was  also  the 
case  with  liquor  obtained  by  scalding  the  leaves  of  the 
indigo  plant  in  large  earthen  bottles.  The  liquor  thus 
obtained,  always  became  of  a  yellowish  green,  and  the 
bottles  containing  it,  being  inverted  in  a  large  vessel  of 
water,  the  liquor  remained  unchanged  for  a  month;  but, 
being  taken  out,  and  atmospheric  air  freely  admitted  to 
the  liquor,  greenish  blue  veins  were  observed  to  spread, 
from  the  surface  doxvmvard,  until  the  whole  became  blue; 
and  then  a  precipitation  of  indigo  soon  commenced.  This 
experiment  was  often  repeated  with  the  same  result;  and 
Dr.  Roxburgh  justly  infers  from  it,  that  carbonic  acid  is 
not  the  agent,  by  which  the  colouring  matter  of  indigo 
"  is  separated  from  its  menstruum."  Some  of  the  same 
■  green  liquor,  being  impregnated  with  nitrogene,  from 
iron  filings,  and  diluted  nitrous  acid,  (in  Dr.  Nooth's  ap- 
paratus) a  violet-coloured  film  was  produced,  after  some 
hours;  but  no  other  change  took  place,  until  the  admis- 
sion of  atmospheric  air,  when  the  usual  granulation  and 
precipitation  of  indigo  soon  followed. 

Some  of  the  same  green  liquor,  being  impregnated,  in 
the  same  way,  with  hydrogene,  from  iron  filings  and  di- 
luted sulphuric  acid,  it  "  was  quickly  covered  with  much 
of  a  deep  voilet-coloured  scum,  but  no  decomposition 
took  place,  till  the  atmospheric  air  had  obtained  access 
to  the  liquor,  when  it  quickly  became  of  a  deep  greenish 
blue,  and  let  fall  a  considerable  proportion  of  precipitate, 
which,  on  drying,  turned  out  to  be  the  most  beautiful 
indigo." 

In  addition  to  these  experiments,  Dr.  Roxburgh  tried 
repeatedly,  with  the  same  green  liquor,  admixtures  of 
lime  water,  volatile  alkali,  caustic  lye,  stale  urine,  prus- 
siate  of  potash,  Sec.  and  they  all  concurred,  says  he,  to 


136  Philosophy  of  Permanent  Colours* 

"  prove  clearly,  that  the  most  powerful  precipitants,  add- 
ed to  these  liquors,  cause  no  decomposition ^  without  the 
help  of  the  open  air,^^ 

Though  Dr.  Roxburgh  had  thus  ascertained,  the  in- 
dispensable necessity  of  somethings  obtained  from  the  open 
air,  to  produce  a  granulation,  and  precipitation  of  indigo, 
and  though  he  had  also  ascertained  that  this  thing,  could 
not  be  either  carbonic  acid  gas,  or  nitrogene,  or  hydro- 
gene,  or  ammonia;  he  did  not  suspect  it  to  be  oxygene, 
until  the  former  edition  of  this,  my  first  volume,  had 
fallen  into  his  hands;  then  however,  (as  I  had  predicted) 
he,  with  laudable  candour,  relinquished  his  belief  of  the 
supposed  agency  of  phlogiston,  in  producing  these  ef- 
fects; and  declared  himself  convinced,  that ''  oxygene 
is  the  colouring  principle  of  indigo."^ 

*  The  following  is  extracted  from  a  letter  written  by  Dr.  Rox- 
burgh, to  Robert  Wissett,  esq.  and  dated  Calcutta,  29th  October, 
1797. 

"  I  have  seen  the  heads  of  my  essay  on  indigo  published,  and 
commented  upon  by  Dr.  Bancroft.  In  consequence  of  seeing  so  good 
an  use  made  of  it,  I  am  encouraged  to  send  to  your  care,  by  Mr. 
Brown,  the  surgeon  of  the  Albion,  a  package  of  a  colouring  drug, 
which  I  do  not  imagine  has  ever  reached  Europe,  viz  the  coloured 
tubes  of  the  blossoms  of  JSfyctanthes  arbor  tristis,  of  Linnaeus.  The 
Hindoos  use  them  to  give  a  most  beautiful  orange  colour  to  cotton 
cloths;  but  with  them  the  colour  soon  fades.  I  will  thank  you  to  give 
the  parcel  to  Dr.  Bancroft,  and  also  beg  of  you  to  inform  him,  that  / 
am  now  a  convert  to  his  ofiinion,  viz.  that  vital  air,  or  oxygene,  is  the 
colouring  firincifile  in  indigo.-^'Vhe  hot  water  process  begins  to  be 
used  over  these  provinces,  by  some  of  the  best  manufacturers;  with 
it  they  can  make  indigo,  when  the  iveather  is  too  cold  for  the  usual 
process  of  fermentation,  and  it  gives  a  more  beautiful  and  lighter 
indigo,  like  the  guatamala,  or  fine  Spanish  flora.  I  send  you  a  sam- 
ple of  some  made  by  Mr.  Pope,  of  Cossimbuzar,  a  most  valuable 
fanner.'* 

When  Dr.  Roxburgh  was  lately  in  Europe,  he  obligingly  left 
with  me,  not  only  samples  of  the  indigo  here  mentioned,  (and  which 
is  truly  excellent,)  but  of  many  other  sorts,  manufactured  in  different 
ways,  from  different  kinds  and  species  of  vegetables  yielding  indigo. 


Philosophy  of  Permanent  Colours.  137 

M.  Berthollet  seems  not  to  have  well  understood  the 
effect  of  some  parts  of  the  process  lately  described.  He 
sajs,  torn.  ii.  p.  42,  that  the  atmospheric  air  does  not  ap- 
pear to  intervene  or  partake  in  the  fermentation,  because 
there  is  a  discharge  of  inflammable  air.  But  it  was  fully 
ascertained  by  Dr.  Roxburgh,  that  a  copious  absorption 
of  air  from  the  atmosphere,  did  occur;  and  that  oxygene 
did  combine  with  the  basis  of  indigo,  in  a  considerable 
degree,  during  the  fermentation,  was  manifested  by  the 
progressive  change,  which  as  usual  constantly  took  place 
in  the  colour  of  the  liquor,  during  the  fermentation,  until 

and  with  different  precipitants,  &c.;  all  serving  either  to  confirm 
or  illustrate  particular  facts  respecting  this  interesting  subject:  but 
a  distinct  account  of  them  would  occupy  too  much  space. 

The  scalding,  or  "  hot  water  process,"  mentioned  in  the  preceding 
extract,  had  been  previously  recommended  by  Dr.  Roxburgh,  and 
is,  indeed,  absolutely  necessary  to  obtain  indigo  from  the  leaves  of 
the  nerium  tinctorum,  which  affords  none  by  fermentation,  with 
water  moderately  warm.  It  is  employed,  as  the  Doctor  informs  us, 
by  "  the  natives  throughout  the  northern  provinces  or  Circars," 
(of  Coromandel)  and  "  in  many  parts  of  the  Carnatic,"  in  making 
indigo  from  the  common  indigo  plant.  Among  the  advantages  sta- 
ted to  result  from  it,  are, — First,  that  of  a  more  complete  and  cer- 
tain extraction  of  the  basis  of  indigo,  (by  thus  subjecting  the  plant 
to  the  action  of  water,  heated  to  about  1 50°,  or  1 60®,  of  Fahrenheit's 
scale,)  than  can  be  expected  by  the  fermenting  process;  with  which 
the  plant,  as  M.  de  Cossigny  asserts,  (Treatise  on  Indigo,  p,  145,) 
will  yield  indigo,  upon  being  fermented  a  second  time. — Second, 
that  of  not  injuring  the  health  of  labourers  employed  in  it;  the  car- 
bonic acid  gas,  and  putrid  miasma  exhaied  by  it,  being  much  less 
than  by  the  fermenting  process — Third,  that  of  requiring  less  agi. 
tation;  because  the  heat  employed,  greatly  promotes  the  absorption 
and  combination  of  oxygene. — Fourth,  that  of  completing  the  ope- 
ration much  sooner,  so  that  it  may  be  performed  two  or  three  limes 
daily,  upon  a  large  scale. — Fifth,  that  of  affording  indigo,  which 
dries  quickly,  without  acquiring  any  bad  smell;  and  which  «  has 
never  that  flinty  appearance  common  to  fermented  indigo;  but  in 
softness  and  levity  is  like,  or  even  superior,  to  Spanish  flora." 

Vol.  I.  S 


1S8  Philosophy  of  Permanent  Colours. 

it  acquired  a  full  green,  and  even  blueish  colour,  the  froth 
or  scum  becoming  more  or  less  blue,  at  the  same  time; 
this  change  was  not  unknown  to  M.  Berthollet,  but  in- 
stead of  ascribing  it  to  the  oxygenation  of  the  indigo  ba- 
sis, he  supposed  it  to  result  from  the  separation,  or  des- 
truction of  a  yellow  substance,  which  gave  the  plant  a 
greenish  tint;  thus  intimating,  that  the  indigo  had  existed 
naturally  of  a  blue  colour  in  the  plants  which  certainly  is 
not  the  fact. 

Some  of  the  manufacturers  of  this  commodity,  in  the 
East  Indies,  have  lately  purified  their  indigo,  by  taking 
it  immediately  from  the  small  dripping  vats^  and  boiling  k 
in  copper  vessels,  with  water  and  fossil  alkali,  (soda),  and 
afterwards  carrying  it  to  what  are  called  the  dripping  ta- 
^/«,  to  undergo  the  treatment  usually  employed  for  bring- 
ing it  to  the  form  of  dry  cakes.  In  this  way  those  impuri- 
ties which  soda  can  dissolve,  will  be  separated;  but  others, 
on  which  it  has  no  action,  will  remain.  For  these  Dr. 
Roxburgh,  as  well  as  M.  de  Cossigny,  have  recommend- 
ed the  application  of  a  diluted  sulphuric  acid,  which  is 
said  also  to  brighten  the  colour;*  as  indeed  it  might  be 

*  Among  the  samples  of  indigo,  with  which  I  was  favoured  by 
Dr.  Roxburgh,  are  three  extracted  from  the  Guatamala  indigo  plant, 
produced  by  seed,  furnished  by  Colonel  Kyd;  and  they  are  stated 
to  have  been  made  on  three  successive  days,  viz. 

On  the  first,  104lbs.  of  leaves  and  shoots  were  cut  at  awn-me*,  and 
by  the  usual  process,  they  yielded  six  ounces  ^1^  of  very  beautiful 
indigo;  i.  e.  at  the  rate  of  one  ounce  from  about  17  lbs.  of  leaves  and 
shoots. 

On  the  second  day,  64lbs.  of  leaves  and  shoots,  also  cut  at  sun- 
rise, yielded  in  the  same  way,  four  ounces  -^^^  of  very  fine  indigo, 
or  at  the  rate  of  one  ounce  from  less  than  1 61bs.  of  the  leaves  and 
twigs.  This  indigo  was  washed  with  diluted  sulphuric  acid,  and 
three  several  times  afterwards,  with  hot  water;  and  though  the  pro- 
duce was  largest,  the  colour  was  a  little  the  brightest. 

On  the  third  day,  56lbs.  of  the  leaves  and  twigs  were  cut  at  noon^ 
the  sun  having  shone  upon  them  several  hours;  they  produced  in 


Philosophy  ofFermanent  Colours.  13  ^ 

expected  to  do,  in  the  way  that  the  colour  of  indigo  dis- 
solved by  it  for  the  Saxon  blue,  is  brightened.  Probably 
the  diluted  Sicidy  here  recommended,  will  not  be  capable 
of  diminishing  the  colouring  matter  of  indigo,  by  dis- 
solving and  removing  any  part  of  it:  but  if  there  were 
any  danger  of  this,  it  would  be  advisable  to  substitute 
the  muriatic  acid,  which  could  have  no  such  effect,  upon 
the  indigo  itself,  though  it  is  equally  efficacious  in  dissol- 
ving all  other  matters  likely  to  be  mixed  with  indigo.  It 
is,  however,  doubtful,  whether  any  considerable  advan- 
tage would  result  from  these  applications:  they  could 
add  nothing  to  the  tingent  power  of  the  indigo,  though 
they  might  improve  its  appearance;  but  even  this  could 
not  be  done  without  such  a  diminution  of  its  weight,  as 
would  counterbalance  the  latter  advantage,  and  in  gene- 
ral dyers  know  how  to  avail  themselves  fully  of  the  tin- 
gent particles  of  indigo,  whatever  extraneous  matter  it 
may  contain. 

Besides  the  several  species  of  indigofera,  already  men- 
tioned, and  the  Nerium  tinctorium,  (respecting  which  I 
must  refer  to  Dr.  Roxburgh's  publication,  in  the  xxviiith 
vol.  of  Transactions  of  the  Society  of  Arts,  &c.)  there  are 
several  plants  which  possess  the  basis  of  indigo,  though 
the  characters  of  some  of  them  have  not  been  well  ascer- 
tained. This  latter  observation,  however,  is  not  applica- 

the  same  way  three  ounces  -^  of  pure  indigo;  i.  e.  one  ounce  from 
about  19lbs.  of  leaves  and  twigs.  This  indigo  was,  I  believe,  intrinsi- 
cally the  best,  but  hke  that  of  the  first  day,  was  not  washed;  and  the 
colour,  though  very  beautiful,  was  in  brightness  a  little  inferior  to 
that  of  the  second  day. 

Considering  that  the  leaves  and  shoots  were  cut  at  noon,  on  the 
third  day,  when  the  rays  of  the  sun  might  be  expected  to  cause  an 
exhalation  of  much  aqueous  vapour,  it  is  surprising  that  so  little  in- 
digo was  obtained. 


140  Philosophy  of  Permanent  Colours* 

ble  to  a  plant  lately  found  by  Dr.  Roxburgh,  to  afford  in- 
digo, and  by  him  denominated  indigofera  ccerulea,  [car- 
neeli  of  the  Telingas,)  of  which  he  has  also  given  a  minute 
description  in  the  vohime  just  mentioned;  and  from  the 
leaves  of  which,  says  he,  "  I  have  often  extracted  a  most 
beautiful  light  indigo."* 

There  is,  moreover,  a  plant,  belonging  to  a  very  dif- 
ferent class,  first  mentioned  as  producing  indigo,  I  be- 
lieve by  Mr.  Marsden,  in  his  History  of  Sumatra,  p. 
78,  under  the  name  of  taroom  akkar.  He  describes  it 
''  as  a  vine,  or  creeping  plant,  with  leaves  four  or  five 
inches  long,  in  shape  like  (those  of)  a  laurel^  but  finer, 
and  of  a  dark  green  colour;"  he  adds,  that  "  by  reason 
of  the  largeness  of  the  foliage,  it  yields  a  greater  propor- 
tion of  sediment."  This  plant  Dr.  Roxburgh  considers  as 
a  species  of  asclepias,  or  swallow-wort,  and  has  added  to 
it  the  trivial  or  specific  name  of  tinctoria.  It  appears  to 
be  nearly  related  to  the  nerium;  both  belonging  to  the 
natural  order  of  contortce,  and  both  yielding  their  colour- 
able matter  from  the  leaves,  most  copiously,  by  hot 
water.f  It  was  brought  from  Sumatra,  and  widely  dis- 

*  I  have  now  before  me  seven  specimens  of  indigo,  given  to  me 
by  Dr.  Roxburgh,  and  made  by  him  from  the  indigofera  coerulea, 
with  the  help  of  hot  water,  to  extract  the  colourable  matter.  They 
arc  similar  to  the  same  number  of  samples  which  the  Doctor  sent  in 
1793,  with  a  description  of  the  plant,  to  Mr.  Ross,  at  Madras,  to  be 
forwarded  to  the  Court  of  Directors  of  the  India  Company,  and  are 
all  very  fine  blue  or  violet  indigo;  particularly  four  of  the  seven, 
which  in  appearance  and  eflTect,  are,  in  my  judgment,  equal  to  the 
finest  fl^ora  of  Guatamala. 

t  Dr.  Roxburgh  has  favoured  me  with  three  samples  of  indigo, 
which  he  obtained  from  the  asclepias  tinctoria,  by  hot  water;  one  is 
a  very  fine  violet-coloured  indigo;  another  is  more  inclined  to  blue, 
and  the  third  to  purple;  the  two  last  were  specifically  a  little  heavier 
than  the  first;  the  worst  of  them,  however,  would,  I  think,  be  con- 
sidered as  worth  8«.  per  pound. 


Philosophy  of  Permanent  Colours*  141 

tributed  in  Bengal,  about  the  year  1791;  is  perennial, 
and  easily  propagated  by  layers,  slips,  or  cuttings.  I  men- 
tion these  particulars,  because  I  shall  have  occasion  to 
refer  to  them  presently,  in  regard  to  a  substance  deno- 
minated barasat  verte. 

Professor  Thomas  Martyn,  mentions  the  galega  tinc- 
toria,  as  being  the  plant  from  which  the  inhabitants  of 
Ceylon  prepare  their  indigo,  which  yields  a  pale  blue 
dye  (see  his  edition  of  Millar's  Gardener's  Dictionary.) 
He  also  mentions,  on  the  respectable  authority  of  Lou- 
reiro,  that  the  spilanthus  tinctoria  is  cultivated  in  Chi- 
na, and  Cochinchina;  that  the  leaves  bruised,  yield  a 
most  excellent  blue  colour,  and  a  green,  prepared  by  a 
method  more  easy  than  from  indigo,  and  not  inferior  in 
brightness. 

Linnasus  says,  the  Swedes  obtain  a  blue  colour  from 
the  scabiosa  succisa,  by  treating  it  like  the  isatis  tincto- 
ria, or  woad  plant;  and  I  have  been  informed,  that  the 
cheiranthus  fenestralis,  or  cluster-leaved  stock  gillyflow- 
er, is  also  capable  of  yielding  indigo.  This  may  be  easily 
ascertained. 

Besides  plants  of  the  genus  of  indigofera  in  Africa, 
we  have  reason  to  believe  there  arc  several  belonging  to 
other  genera,  capable  of  producing  indigo.  Dr.  Winter- 
bottom  says,  **  there  is  now  no  room  to  question  that 
the  blue  dye,  commonly  used  by  the  natives  of  the 
windward  coasty  is  not  indigo,  but  is  obtained  from  a 
very  different  plant."  He  adds,  "  a  few  roots  of  it,  I  am 
informed,  have  lately  been  planted  within  the  settlement 
(of  Sierra  Leone,)  so  that  an  accurate  description  of  it 
may  soon  be  hoped  for."  Probably,  this  is  the  plant  to 
which  Professor  Afzelius  alluded,  when,  upon  his  re- 
turn from  Sierra  Leone  some  years  ago,  he  told  me  he 
had  discovered  a  new  plant  producing  indigo,  of  which 
he  intended  soon  to  publish  a  description.  Dr.  Winter- 


142  Philosophy  of  Permanent  Colours. 

bottom  also  states,  on  the  authority  of  M.  Isart,  (Reise 
nach  Guinea)  that  on  the  gold  coast,  the  negroes,  in- 
stead of  the  indigo  plant,  infuse  "  the  leaves  of  a  spe- 
cies of  bignonia,  and  the  root  of  a  species  of  tabernae- 
montana,  with  a  lye  of  wood  ashes,  to  dye  cotton  blue." 
See  his  account  of  the  Native  Africans,  vol.  i.  p.  97. 
The  amorpha  fruticosa,  and  the  sophora  tinctoria,  Lin. 
also  afford  coarse  sorts  of  indigo. 

This  production  often  differs  greatly  in  regard  to  its 
specific  gravity,  some  indigo  being  lighter  than  water; 
and  the  lightest  being  always,  and  justly,  the  most  es- 
teemed; because  it  is  always  the  purest,  excepting  only 
when  the  comparative  w^eight  has  been  increased,  by 
\ try  forcible  pressure^  to  separate  the  water,  and  accele- 
rate the  drying,  that  it  may  not  be  in  danger  of  be- 
coming mouldy.*  Indigo  is  sometimes  adulterated,  by 
fraudulently  adding  to  it  various  gummy,  resinous, 
earthy,  and  mucilaginous  matters,  and  particularly  an 
extract  from  the  fruit  of  the  embryopteris  glutinifera, 
denominated  gaub  in  the  East  Indies.  It  is  also  render- 
ed both  heavier  and  less  pure,  by  employing  lime  too 
copiously,  as  a  precipitant,  which  not  only  subsides, 
mixed  with  the  indigo,  but  also  throws  down  many 
other  useless  matters.  This  also  happens  in  a  greater  or 
lesser  degree  with  other  precipitants,  when  used  in  ex- 
cess, and  more  especially  with  alum. 

Indigo  also  differs  in  regard  to  its  colour,  e.  g.  the 
Guatamala,  which  has  long  been  the  most  esteemed  of 

*  Quatremere  Dijonville  asserts,  and  I  believe  truly,  that  indigo 
closely  packed,  and  secluded  from  atmospheric  air,  will  soon  be- 
come hot,  and  undergo  some  degree  of  fermentation,  by  which 
white  specks  will  be  formed  within  the  cakes  of  indigo.  See  his 
"  Analyse  et  examen  Chemique  de  Tlndigo,  Sec."  Mem.  des  s§av, 
etrang.  torn.  ix.  Indigo  in  drying  should  always  be  shaded  from  the 
sun,  and  a  free  current  of  air  be  made  to  pass  over  it. 


Philosophy  of  Permanent  Colours,  145 

all  the  varieties  of  x\merican  indigo,  is  divided  into 
three  sorts;  of  which  the  first,  called  by  the  Spaniards 
flora ^  has  a  very  fine  blue  colour;  the  second,  which 
bears  the  name  sobre  salliente,  is  violet;  and  the  third, 
named  corti-color^  is  copper-coloured.  When  the  first 
of  these  is  sold  at  9^.  the  pound,  the  second  is  com- 
monly thought  to  be  worth  7^.  and  the  third  5s.  6d, 
Of  the  East  Indian  indigo,  that  of  Java  was  formerly 
most  esteemed,  but  since  the  manufacture  of  this  com- 
modity has  so  much  engaged  the  attention  of  the  Bri- 
tish inhabitants  in  that  part  of  the  world,  indigo  supe- 
rior even  to  that  of  Guatamala,  has  been  imported,  in 
considerable  quantities,  from  the  British  possessions 
there:  And  of  this,  the  finest  blue  commonly  sells  20 
per  cent,  higher  even  than  the  finest  glowing  purple, 
(though  the  last  probably  contains  nearly  as  much  co- 
louring matter  as  the  first,)  and  70  or  80  per  cent, 
higher  than  the  best  copper-coloured.  The  price  has,  I 
believe,  also,  been  sometimes  affected  in  this  country, 
by  the  size  and  form  of  the  indigo  cakes;  the  large  and 
square  selling  for  more  than  those  which  are  flat  and 
thin,  and  these  last  for  more  than  broken  indigo,  though 
it  must  all  be  broken  and  powdered,  before  it  can  be 
advantageously  used. 

M.  Berthollet  has  proposed  to  ascertain  the  compara- 
tive values  of  different  parcels  of  indigo,  by  dissolving 
equal  portions  of  each  in  sulphuric  acid,  and  afterwards 
destroying  their  colour  by  adding  the  oxymuriatic  acid 
to  them,  severally;  always  considering  that  indigo  as 
most  valuable,  which  requires  the  greatest  portion  of 
oxymuriatic  acid  for  the  extinction  of  its  colour.  But 
probably  the  relative  quantity,  and  value  of  colouring 
matter,  in  any  parcel  of  indigo,  might  be  as  well  mea- 
sured, or  ascertained,  without  employing  the  oxymu- 
riatic acid,  by  mixing  a  certain  portion  of  the  indigo. 


i4M  Philosophy  of  Permanent  Colours. 

when  dissolved  by  sulphuric  acid,  with  a  certain  quan- 
tity of  water  in  a  glass,  and  comparing  the  depth,  or 
fullness  of  its  colour,  with  that  of  other  indigo  treated 
in  the  same  way,  and  taken  as  a  standard  or  point  of 
comparison.  But,  after  all,  there  will  be  so  much  in- 
equality in  the  different  pieces  or  cakes  of  indigo,  as  it 
is  commonly  assorted,  in  any  one  package,  that  consi- 
derable uncertainty  must  attend  any  method  of  ascer- 
taining its  true  value,  by  trials  with  small  parts  or 
samples  only. 

The  most  accurate  analysis  of  indigo,  with  which  I 
am  acquainted,  is  that  recently  made  by  M.  Chevreuil. 
He  took  for  this  analysis  the  best  Guatamala  indigo, 
and  found  that  by  digestion  in  hot  water,  it  yielded  to  the 
latter,  ammonia,  indigo  at  the  minimum  of  oxidation*^ 
combined  with  ammonia,  a  particular  green  matter,  in 
union  with  ammonia,  gum,  and  a  small  quantity  of 
yellow  extractive  matter;  amounting  all  together  to  12 
parts  for  every  100  of  the  indigo  employed.  From  the 

*  What  is  here  called  indigo  at  the  minimum  of  oxidation,  ought 
to  be  rather  considered  as  the  basis  of  indigo;  for  while  it  is  sus- 
ceptible of  dissolution,  either  by  water,  or  alcohol  alone,  it  does  not 
possess  the  properties,  nor  strictly  deserve  the  name  of  indigo, 
though  capable  of  acquiring  the  former,  and  deserving  the  latter, 
by  a  sufficient  addition  of  oxygene.  The  existence  of  this  basis,  or 
of  indigo  at  the  minimum  of  oxidation,  in  the  best  Guatamala  in- 
digo, proves  the  difficulty  of  thoroughly  combining  the  former, 
with  hi  full  fior/iortion  of  oxy^Gne  by  the  usual  process;  and  if  it  be 
thus  contained  in  Guatamala  indigo,  how  much  more  of  it  will  have 
been  left  suspended  and  lost  in  the  beating  vat,  as  commonly  ma- 
naged? M.  BerthoUet  mentions,  probably  from  personal  observa- 
tion, that  in  Egypt,  the  indigo-making  process  is  so  badly  conducted, 
that  the  indigo  produced  by  it,  is  always  greenishy  ("  verdatre")  and 
gives  a  bad  colour;  and  that  it  is  so  much  disposed  to  dissolve  by 
fermentation,  that  the  dyers  need  only  mix  a  little  broivn  sugar 
with  it  in  the  vat,  to  excite  one,  sufficient  to  render  it  fit  for  dye- 
ing. An  effect  which  could  only  result  fi'om  a  deficient  oxygena- 
tion. See  Elements,  8cc.  torn.  ikp.  41. 


Philosophy  of  Permanent  Colours.  145 

remaming  88  parts  he  obtained  by  digestion  with  alco- 
hol, 30  parts,  consisting  of  a  green  matter,  a  reddish 
resin,  and  a  little  indigo.  By  digesting  the  residuum 
with  muriatic  acid,  he  obtained  6  parts  of  "  resine 
rouge, ''^  2  parts  of  carbonate  of  iron,  and  2  parts  of  red 
oxide  of  iron,  in  union  with  alumine;  after  these  had 
been  all  separated,  there  remained  about  three  parts  of 
siliceous  earth,  and  45  parts  of  pure  indigo.  This  last, 
but  no  other  part,  was  capable,  when  burning,  of  emit- 
ting that  beautiful  purple  smoke^  by  which  indigo  is 
peculiarly  distinguishable;  and  which  consists  of  indigo, 
rendered  volatile  by  heat,  without  any  decomposition. 
He  concluded  from  this  analysis,  and  from  other  expe- 
riments, that  indigo  may  be  purified  "  par  la  voie 
seche,*  et  par  la  voie  humide;"  that  when  purified,  it 
is  susceptible  of  volatilization  and  crystallization:  and 
that,  when  most  purified,  its  colour  is  purple,  rather 
than  blue,  (See  Ann.  de  Chimie,  tom.  68.)  I  think  it 
probable,  however,  that  this  purple  appearance  results 
from  a  greater  condensation  of  the  colouring  matter  of 
indigo;  since  that  of  Prussian  blue,  when  most  pure, 
exhibits  a  similar  purple  coppery  aspect. 

Bergman  after  separating,  as  far  as  he  was  able,  the 
extraneous  matters  mixed  with  indigo,  found  that  100 
parts  of  it  left  47,  which  he  considered  as  its  colouring 
matter,  very  nearly  in  a  state  of  purity;  and  this  being 

*  The  pure  part  of  indigo  may  be  all  converted  to  vapour,  with- 
out any  decomposition,  by  an  elevation  of  temperature,  a  little 
beloiv  the  point  at  which  it  would  be  decomposed,  and  the  simulta- 
neous  application  to  its  surface,  of  a  current  of  any  elastic  fluid, 
which  exerts  no  chemical  affinity  upon  the  indigo.  This,  however, 
will  be  most  advantageously  performed,  with  but  small  quantities 
of  indigo;  for  in  larger,  it  will  suffer  a  partial  decomposition,  if 
kept  for  any  considerable  time  at  such  a  temperature  as  is  neces- 
sary to  render  it  volatile. 

Vol.  I.  T 


146  Philosophy  of  Permanent  Colours. 

carefully  distilled  by  itself,  yielded  2  parts  of  carbonic 
acid,  8  of  an  alkaline  liquor,  9  of  an  empyreumatic  oil^ 
and  23  of  charcoal;  which  last,  being  burnt  in  the  open 
air,  left  4  parts,  of  which  about  one  half  was  an  oxide 
of  iron,  and  the  remainder  a  fine  siliceous  powder. 

Bergman  supposed  the  blue  colour  of  indigo,  to  re- 
sult from  a  combination  of  iron  with  the  colouring  mat- 
ter of  the  plant,  as  the  colour  of  ink  does  from  the  union 
of  that  metal  with  the  colouring  matter  of  galls,  and  that 
of  Prussian  blue  from  its  union  with  the  prussic  acid. 
But  these  supposed  analogies  are  without  any  founda- 
tion; for  the  proportion  of  iron  is  not  only  by  much  too 
small  to  produce  such  an  effect,  but  it  possesses  no 
affinity  for  the  basis  of  indigo^  nor  the  least  power  of 
influencing,  or  contributing  to  its  colour. 

M.  de  Chaptal,  (who  as  a  minister  and  a  chemist, 
has  manifested  a  great  superiority  of  intellect,  and  of 
science,)  appears  to  think,  that  in  the  fermentation 
of  indigo,  charcoal  greatly  contributes  to  produce  its 
blue  colour;  "  la  dissolution  des  vegetaux,  (says  he,) 
donne  un  charbon  d'un  tres  beau  bleu,  et  il  est  proba- 
ble, qui  lorsque  la  coulcur  bleu  est  develloppee  par  la 
fermentation,  le  carbone  est  presque  mis  a  ««,  et  qu'il 
reste  en  combinaison  avec  une  huile,  qui  ajoute  a  la 
iixite  de  la  couleur,  et  indique  le  dissolvant  le  plus  con- 
venable."  (Chim.  appl.  aux  Arts,  tom.  ii.  p.  406.)  But 
if  this  reasoning  were  just,  why  is  it  that  so  few  vege- 
tables can  be  made  to  produce  indigo,  though  all  of 
them  contain  the  basis  of  charcoal;  and  what  becomes 
of  the  supposed  charcoal,  when  by  depriving  indigo  of 
its  oxygene,  in  the  way  which  will  be  hereafter  explain- 
ed, the  basis  of  it,  dissolved  and  secluded  from  atmos- 
pheric air,  is  rendered  colourless^  and  pellucid^  until  by 
the  re-admission  of  oxygene,  its  colour  is  reproduced? 
Certainly  there  is  no  instance  in  which  charcoal  has 


Philosophy  of  Permanent  Colours,  147 

been  rendered  colourless  by  an  abstraction  of  oxygene, 
and  afterwards  black,  by  the  re-union  of  it.  Probably, 
the  only  similitude  between  charcoal  and  indigo,  is  that 
which  I  formerly  pointed  out;  i,  e.  that  in  each,  the 
basis  combines  with  oxygene,  and  thereby  acquires 
colour  and  stability;  with  a  complete  indissolubility  in 
the  former,  and  a  very  difficult  solubility  in  the  latter. 
But  as  their  bases  are  different,  so  are  their  respective 
colours,  and  several  of  their  other  properties. 

The  colouring  matter  of  all  sorts  of  indigo,  is  nearly 
the  same,  and  capable  of  giving  nearly  similar  shades 
of  colour,  when  the  basis  has  been  sufficiently,  but  not 
excessively  oxygenated.  The  impure  or  extraneous 
matters,  mixed  with  it  either  unavoidably,  or  fraudu- 
lently, are  many  and  various;  and  they  may  be  gene- 
rally dissolved  or  separated,  by  the  means  employed  by 
M.  Chevreuil;  but  when  this  has  been  done,  there  are 
very  few  chemical  agents,  capable  of  acting  upon  the 
residual  pure  colouring  matter  of  indigo,  duly  consti- 
tuted. There  is,  indeed,  but  one  way,  in  which  it  can 
be  dissolved,  without  injuring  its  basis,  and  diminish- 
ing the  stability  of  its  colouring  matter;  and  this  is, 
not  by  any  single  agent,  but  by  the  co-operation  of  se- 
veral: of  these,  the  first  are  such  as  by  possessing  a 
greater  affinity  for  oxygene,  than  that  which  is  exerted 
by  the  basis  of  indigo,  are  enabled  to  deoxygenate  the 
latter,  or  at  least  deprive  it  of  a  great  portion  of  its  oxy- 
gene, so  as  afterwards  to  render  it  soluble,  by  means 
which  otherwise  would  be  incapable  of  acting  upon  it; 
particularly  lime,  and  the  several  alkalies,  in  their  caus- 
tic state. 

The  matters  employed  to  deprive  indigo  of  its  oxy- 
gene, and  thereby  render  it  soluble,  are  either  vegetable, 
animal,  or  mineral.  The  vegetable  are  chiefly  such  as 
excite,  or  promote,  fermentation;  and  indigo  seems  to 


148  Philosophy  of  Permanent  Colours. 

have  been  exclusively  employed  with  these,  for  some 
time  after  it  was  first  made  known,  for  dyeing  in  Eu- 
rope. Until  that  period,  blue  colours  had  only  been 
dyed  by  the  woad,  as  I  have  already  mentioned;  and  it 
being  erroneously  believed,  that  the  colours  of  indigo, 
if  employed  by  itself,  would  prove  fugitive,  it  was  in 
some  countries  totally  prohibited,  in  others  only  per- 
mitted to  be  used  when  mixed  with  about  one  hundred 
times  its  weight  of  woad,  in  what  was  called  the  woad- 
vat.  This  was,  and  continued  to  be,  the  case  in  France, 
even  under  the  enlightened  administration  of  Colbert, 
and  afterwards  until  the  year  1737;  when,  in  conse- 
quence of  the  experiments  and  representations  of  M. 
Dufay,  a  new  regulation  was  issued  by  the  French  go- 
vernment, permitting  the  dyers  to  employ  indigo  either 
alone,  or  with  woad,  at  their  option.  The  preparation 
of  the  woad- vat,  under  the  name  of  Cuve  de  Pastel, 
was  minutely  described  by  Hellot,  (Art  de  la  Teinture, 
chap.  10,)  as  it  has  been  since,  more  correctly,  by 
Quatremere,  Berthollet,  Chaptal,  and  others;  it  is,  be- 
sides, so  well  known  to  practical  dyers,  that  a  particular 
account  of  it  from  me  cannot  be  wanted  by  them,  and 
it  would  be  superfluous  to  my  other  readers,  who  need 
only  to  be  informed,  that  the  woad  is  brought  to  fer- 
ment by  first  pouring  over  it  a  boiling  decoction  of 
weld,  madder,  and  bran,  and  by  keeping  it  afterwards 
in  a  suitable  temperature,  until  blue  veins  appear  on 
the  surface  of  the  liquor.  Quick  lime  is  then  added  to 
it,  and  also  the  proper  quantity  of  indigo,  finely  ground 
with  a  small  portion  of  water;  the  mixture  is  then  well 
stirred,  and  afterwards  covered  over;  and  such  other 
means  are  employed  as  may  be  necessary  to  keep  up 
the  proper,  and  only  the  proper,  degree  of  warmth  and 
fermentation,  until  a  sufficient  deoxygenation^  and  solu- 
tion of  the  indigo,  has   taken  place,  which    may  be 


Philosophy  of  Permanent  Colours.  149 

known  by  the  blue  or  shining  coppery  colour  of  the 
Jiquor  on  its  surface,  (where  the  indigo  is  constantly 
revived  by  an  absorption  of  oxygene),  and  by  its  green 
tint  every  where  below  the  surface.  With  these  ap- 
pearances, the  liquor  will  be  fit  for  dyeing,  and  though 
the  colour  which  it  gives  to  wool  or  cloth  will  be  green, 
when  first  taken  out  of  the  dyeing  liquor,  it  will  very 
speedily  become  blue,  when  exposed  to  the  air,  by  at- 
tracting and  regaining  the  oxygene  taken  from  it  during 
the  fermenting  process;  the  abstraction  of  which  was 
the  cause  of  its  green  colour. 

It  has  hitherto  been  found  extremely  difficult  to 
attain  the  proper,  and  only  the  proper,  degree  of  fer- 
mentation, in  conducting  the  woad-vat;  and  this  diffi- 
culty seems  to  have  resulted  principally  from  the  ever 
varying  properties  of  the  woad,  as  it  has  been  commonly 
and  ignorantly  prepared.  Indeed,  there  is  good  reason 
to  believe,  that  it  would  be  much  better  if  the  manu- 
facturers of  this  article  would  wholly  abstain  from  giv- 
ing it  any  sort  of  fermentation,  [which  at  best  is  certainly 
unnecessary) y  and  content  themselves  with  barely  grind- 
ing the  plant,  and  drying  it  as  expeditiously  as  possible, 
forming  it  into  balls  at  the  proper  time.  Much  also  de- 
pends upon  the  quantity  of  lime  employed;  not  only  for 
the  purpose  of  dissolving  the  indigo,  but  also  for  that 
of  moderating  the  fermentation;  which,  when  excessive, 
induces  a  putrefactive  process,  and  destroys  the  tingent 
power  both  of  the  isatis  and  indigo.  Too  much  lime, 
on  the  contrary,  obstructs  the  necessary  degree  of  fer- 
mentation; the  colour  of  the  liquor  then  becomes  black- 
ish, and  the  vat  remains  useless,  until  the  obstacle  has 
been  overcome,  by  the  addition  of  matters  suited  to 
counteract  this  excess.  This  vat,  or  preparation  of  indi- 
go and  woad,  is  very  generally  employed  for  dyeing 
wool  and  woollen  cloth  or  stuffs. 


ISO  Philosophy  of  Fermanent  Colours, 

Indigo  is  moreover  dissolved,  without  any  admixture 
of  woad,  in  a  vat  which  Hequet  d'Orval  et  Ribaucourt, 
Berthollct,  and  others,  have  described  under  the  name 
of  Cuve  d'Inde,  or  Indigo-vat;  and  which  is  also  well 
known.  For  this  the  indigo  being  ground  with  a  little 
water,  its  deoxygenation  is  produced  by  bran  and  mad- 
der, (acting  as  vegetable  ferments,)  and  its  dissolution 
by  potash.  This  is  liable  to  fewer  failures  than  the  for- 
mer vat,  but  it  is  more  costly,  and  is  chiefly  employed 
to  dye  silk.  When  fit  for  use,  the  surface  of  the  liquor 
exhibits  a  blue  scum,  intermixed  with  patches  of  a 
shining  coppery  colour,  and  the  mass  below  the  surface 
appears  of  a  fine  green. 

The  only  vat  in  which  animal  matters  are  made  to 
co-operate  in  the  deoxygenation  of  indigo,  is  that  with 
urine,  now  but  little  used,  except  as  a  domestic  dye  for 
small  woollen  articles;  madder,  or  some  other  vegetable 
ferment,  is  commonly  added  to  assist  in  abstracting  the 
oxygene,  and  when  this  is  done,  the  ammonia,  or  vola- 
tile alkali,  of  the  urine,  produces  a  dissolution  of  the 
indigo. 

The  influence  of  mineral  agents  in  the  deoxygenation 
of  indigo,  is  yet  more  obvious  and  interesting  than  that 
of  animal  or  vegetable  ferments;  and  the  former  are, 
therefore,  advantageously  employed  by  dyers  and  cali- 
co printers,  in  fixing  the  colour  of  indigo  upon  linen 
and  cotton.  Of  these  the  principal  is  the  oxide  of  iron, 
at  a  low  degree  of  oxygenation,  as  it  exists  in  the  sul- 
phate of  that  metal.  Dr.  Priestley  appears  to  have  first 
noticed  the  powerful  attraction  exerted  by  this  sulphate, 
or  by  the  oxide  recently  precipitated  from  a  solution  of 
It,  upon  the  oxygene  of  the  atmosphere,  though  its  use, 
in  promoting  the  dissolution  of  indigo,  had  been  pre- 
viously discovered  by  dyers,  but  without  their  having 
had  any  suspicion  of  its  mode  of  action. 


Philosophy  of  Permanent  Colours,  151 

Indigo  moistened,  and  finely  ground,  being  put  into 
warm  water,  with  twice  its  weight  of  sulphate  of  iron, 
and  the  same  quantity  (as  the  latter)  of  pure  lime,  re- 
cently and  well  burnt,  will,  with  a  little  stirring,  be 
dissolved  in  twenty -four  hours.  In  this  mixture,  a  part 
of  the  lime  unites  with  the  sulphuric  acid,  forming  cal- 
careous sulphate,  or  selenite,  and  at  the  same  time  pre- 
cipitates the  oxide  of  iron,  which,  not  being  saturated 
with  oxygene,  attracts  so  much  of  that  which  was  com- 
bined with  the  indigo,  as  to  render  this  last  soluble  by 
the  lime  in  excess,  above  that  which  was  required  to 
saturate  the  sulphuric  acid.  The  beginning  dissolution 
of  the  indigo,  may  be  perceived  by  a  shining  copper- 
coloured  pellicle,  which  forms  itself  on  the  surface  of 
the  mixture,  while  the  liquor  itself  becomes  green,  and 
afterwards  gradually  inclines  more  and  more  to  the  yel- 
low, as  the  solution  advances.  When  it  is  completed, 
and  the  liquor  settled,  the  cotton  yarn  or  stuffs  are  to 
be  dyed  in  it:  they  appear  yellow  when  first  taken  out, 
but  by  absorbing  the  oxygene,  will  rapidly  assume  and 
pass  through  the  different  shades  of  green,  and  in  a  few 
minutes  become  blue;  the  oxygene  regenerating  the  in- 
digo, in  the  pores  of  the  cotton. 

Mr.  Haussman,  of  Colmar,  in  Alsace,  who,  with  a 
considerable  stock  of  chemical  knowledge,  daily  prac- 
tices the  arts  of  dyeing  and  calico  printing,  published 
an  excellent  *'  Memoire  sur  I'indigo,  et  ses  dissolvans," 
in  the  Journal  de  Physique,  &.c.  for  March,  1788,  in 
.which  he  observes,  that  the  change  of  colour  from  yel- 
low to  blue,  in  cottons  dyed  as  before  mentioned,  may 
be  greatly  accelerated,  and  the  blue  rendered  deeper 
and  brighter  than  it  would  otherwise  become,  by  plung- 
ing the  dyed  cottons,  when  first  taken  out  of  the  vat, 
into  water  soured  by  vitriolic  acid,  which  hastens  the 
regeneration  of  the  indigo,  and  moreover  dissolves  and 


15^  Philosophy  ofPermnnent  Colours. 

carries  off  a  portion  of  white  calcareous  sulphate,  or 
selenite,  which  would  otherwise  diminish  the  intensity 
of  the  blue  colour. 

If  the  colour  of  the  vat  be  not  all  used,  soon  after  it 
has  been  prepared,  it  will  require  occasional  stirring, 
since  the  dissolved  indigo,  by  continually  absorbing 
oxygenous  gas  from  the  atmosphere,  will  be  constantly 
revived  upon  the  surface  of  the  liquor;  and,  when  so 
revived,  it  can  only  be  re-dissolved,  by  being  again 
subjected  to  the  combined  action  of  lime,  and  oxide  of 
iron:  if  by  length  of  time  these  should  become  perfectly 
saturated  with  oxygene,  and  carbonic  acid,  before,  the 
blue  colour  is  ajl  used,  a  farther  portion  of  each  must  be 
added,  and  somewhat  more  of  lime  than  of  the  sulphate 
of  iron. 

It  must  be  observed,  that  where  lime  is  the  only  sol- 
vent of  indigo,  as  in  the  vat  last  described,  the  colour  is 
not  sufficiently  condensed  for  dyeing  very  deep  blues; 
and,  therefore,  when  these  are  wanted,  it  is  found  best 
to  increase  the  power  of  the  lime  by  an  addition  of  pot- 
ash, or  vegetable  alkali,  not  exceeding  in  weight  twice 
the  weight  of  the  indigo  to  be  dissolved. 

In  calico  printing,  when  diffi^rent  shades  of  blue  are 
to  be  produced  in  the  same  piece,  the  indigo  finely 
ground  with  sulphate  of  iron,  and  properly  thickened, 
is  first  printed  on  the  calico,  which  after  drying,  is  put 
alternately  into  lime  water,  and  then  into  a  solution  of 
sulphate  of  iron,  in  different  vats,  until  by  these  means 
a  sufficient  abstraction  of  oxygene  is  made  by  the  lat- 
ter, and  a  sufficient  dissolution  of  the  indigo  by  the 
former,  to  fix  the  colour  permanently.  This  is  called 
China  blue,  and  M.  Chaptal  mentions  it  as  an  instance 
in  which  the  colour  is  applied  before  the  mordant.  But 
it  seems  to  me  that  there  is  no  mordant  in  this  opera- 
tion, which  has  for  its  object,  nothi?ig  but  a  dissolution  of 


Philosophy  of  Permanent  Colours.  153 

the  indigo,  which  being  dissolved,  fixes  itself  by  simple 
application. 

Mr.  Haussnian  observes,  that  all  the  precipitates  of 
iron,  whether  obtained  from  solutions  of  that  metal  by 
the  mineral,  vegetable,  or  animal  acids,  will  serve,  with 
quick  lime,  to  dissolve  indigo,  as  well  as  that  of  green 
vitriol,  provided,  and  so  long  as  they  retain  the  property 
of  absorbing  vital  air;  but  that  a  nitric  solution  of  iron, 
or  the  rust  of  it,  or  any  other  preparation,  where  it 
exists  in  an  ochrous  form,  not  attracted  by  the  magnet, 
nor  capable  of  attracting  pure  air,  will  be  wholly  useless 
towards  producing  a  dissolution  of  indigo,  even  though 
employed  with  an  excess  of  quick  lime,  or  of  caustic 
alkali. 

Mr.  Haussman  further  observes,  that  caustic  alkali, 
with  fine  iron  filings,  instead  of  the  precipitate  fromi 
copperas,  would  not  dissolve  indigo;  but  that  (regulus 
of)  antimony,  brought  into  the  form  of  a  powder,  dis- 
solved it  perfectly  with  the  caustic  alkali,  or  quick  lime 
slacked  by  water;  though  the  calces,  or  oxides  of  anti- 
mony, in  this  way,  produced  no  such  effect:  nor  did  any 
precipitates  of  copper:  on  the  contrary,  they  all  seemed 
rather  to  hasten  the  regeneration  of  indigo,  after  it  had 
been  dissolved  by  some  other  means.  This  efiect  of  the 
Qxides  of  copper,  (which  results  from  the  great  facility 
with  which  they  relinquish  their  oxygene)  is  now  well 
known,  and  calico  printers  avail  themselves  of  it  in 
making  what  are  called  reserves,  or  applications  of  ver- 
digrise,  sulphate  of  copper,  or  tobacco-pipe  clay,  and 
glue,  or  in  its  stead,  tallow,  mixed  and  printed  upon  par- 
ticular parts,  intended  to  be  hindered  from  imbibing  the 
indigo  blue,  and  kept  white,  while  the  rest  of  the  piece 
is  dyed.  After  mentioning  this  effect,  it  can  hardly  be 
necessary  to  add,  that  when  the  sulphate  of  iron  is  want- 

VOL.  I.  U 


154  Philosophy  of  Permanent  Colours. 

ed  to  deoxygenate  indigo,  care  should  be  taken  that  it 
be  not  mixed  with  any  oxide  of  copper. 

I  have  repeated  most  of  Mr.  Haussman's  experi- 
ments, with  different  precipitates,  or  oxides  of  iron,  and 
with  effects  nearly  similar  to  those  he  describes.  I  found 
that  neither  the  rust  of  iron,  nor  the  nitric  oxide  of  it, 
would  assist  in  the  dissolution  of  indigo;  obviously  be- 
cause they  were  both  already  saturated  with  oxygene:  I 
also  found,  that  even  the  oxide  precipitated  from  sul- 
phate of  iron,  failed,  and  for  the  same  reason,  when, 
instead  of  separating  it  by  lime,  it  was  obtained  by  dis- 
solving the  sulphate  in  water,  and  leaving  it  for  some 
weeks  exposed  to  the  air  in  warm  weather,  where  the 
iron  was  farther  acted  upon,  and  saturated,  as  well  as 
precipitated,  by  the  oxygene  which  it  gained  from  the 
atmosphere. 

It  is  upon  the  same  principle,  that  the  topical  indigo 
blue,  employed  by  calico  printers,  chiefly  with  the  pen- 
cil, is  made,  only  substituting  for  the  sulphate  of  iron, 
a  portion  of  red*  orpiment,  (sulfure  of  arsenic),  which 
has  a  similar  power,  when  dissolved  by  an  alkali,  of  de- 
priving indigo  of  its  oxygene,  and  thus  rendering  it 
soluble.  The  ingredients  of  this  composition  are  by 
different  persons,  mixed  in  different  proportions,  and 

*  J?erf  orpiment  produces  a  better  effect  than  the  ijeliow,  because 
it  contains  less  oxygene.  The  fact  was  known  long  before  the 
cause.  Until  lately  it  was  supposed,  that  the  red  and  yellow  differ- 
ed only  by  containing  different  proportions  of  sulphur;  and  that 
this  difference  enabled  one  to  act  more  efficaciously  than  the  other, 
in  the  deoxygenation  of  indigo;  but  this  is  not  true.  When  orpi- 
ment is  employed  in  this  way,  the  alkali  precipitates  the  arsenic  in 
its  metallic  form,  depriving  it,  at  the  same  time,  of  a  part  of  its 
sulphur.  After  which,  the  metallic  arsenic  acts  upon  the  indigo,  in 
the  same  way  as  the  oxide  of  iron  does,  when  green  vitriol  is  em- 
ployed, and  by  sufficiently  abstracting  the  oxygene  of  the  indigO; 
enables  the  caustic  alkali  to  dissolve  the  latter. 


Philosophy  of  Pei'manent  Colours.  155 

will  succeed  with  considerable  latitude  in  this  respect; 
indeed,  the  variable  qualities  of  indigo,  render  it  diffi- 
cult to  prescribe  any  exact  proportions,  which  shall 
be  always  equally  efficacious. 

Mr.  Haussman  mixes  twenty-five  gallons  of  water, 
with  sixteen  pounds  of  indigo,  well  ground,  (or  a 
greater  or  smaller  quantity,  according  to  the  quality  of 
the  indigo,  and  the  depth  of  colour  wanted),  to  which 
he  adds  thirty  pounds  of  good  carbonate  of  potash, 
placing  the  whole  over  a  fire;  and  as  soon  as  the  mix- 
ture begins  to  boil,  he  adds,  by  a  little  at  a  time,  twelve 
pounds  of  quick  lime,  to  render  the  alkali  caustic,  by 
absorbing  its  carbonic  acid.  This  being  done,  twelve 
pounds  of  red  orpiment  are  also  added  to  the  mixture, 
which  is  then  stirred,  and  left  to  boil  for  some  little 
time,  that  the  indigo  may  be  perfectly  dissolved;  which 
may  be  known  by  its  giving  a  yellow  colour,  imme- 
diately upon  being  applied  to  a  piece  of  white  transpa- 
rent glass.  M.  Oberkampf,  proprietor  of  the  celebrated 
manufactory  at  Jouy,  near  Versailles,  uses  a  third  more 
of  indigo;  and  others  use  different  proportions,  not  only 
of  indigo,  but  of  lime,  potash,  and  orpiment;  which  all 
seem  to  answer  with  nearly  equal  success;  but  with  the 
best  violet- coloured  Guatamala  indigo,  it  is  certain  that 
a  good  blue  may  be  obtained  from  a  less  quantity  than 
that  prescribed  by  Mr.  Haussman,  by  using  as  much 
recently  burnt  pure  lime,  as  of  indigo,  the  same  quan- 
tity of  orpiment,  and  twice  as  much  potash.  This  com- 
position is  to  be  thickened  by  gum,  which  should  be 
dissolved  in  it  whilst  hot;  and  it  should  afterwards  be 
kept  secluded  as  much  as  possible  from  the  access  of 
atmospheric  aip. 

Indigo  dissolved  in  this  way,  for  penciling  or  printing, 
I  shall  hereafter  call  topical  blue — its  strong  tendency 
to  attract  oxygene  from  the  atmosphere,  and  to  be 


156  Philosophy  of  Permanent  Colours. 

thereby  regenerated,  renders  its  use  subject  to  many 
difficulties;  it  being  almost  impossible  to  pencil,  and 
more  so  to  print  therewith,  a  piece  of  cotton  throughout 
of  the  same  shade,  whatever  pains  may  be  taken  to  apply 
it  equally,  and  quickly,  by  the  most  expert  and  careful 
hands.*  It  will  give  a  fast  colour,  only  so  long  as  it 
continues  yellow,  or,  at  most,  of  a  yellowish  green;  as 
soon  as  it  appears  blue,  the  indigo  may  be  considered 
as  revived,  and  incapable  of  fixing  itself  on  the  cotton: 
in  this  case,  however,  it  may  be  redissolved,  by  adding 
more  caustic  alkali  and  orpiment.  The  clear  liquor  only, 
when  gummed,  is  to  be  used;  but  it  is  not  to  be  separated 
from  the  sediment,  which  helps  to  preserve  it  in  a  state 
of  dissolution.! 

*  Being  at  Manchester  in  1795,  Messrs.  Hoyle  and  Son,  showed 
me  in  confidence,  a  method,  of  their  invention,  for  printing  calico, 
with  the  topical  blue,  expeditiously  and  successfully,  by  employing 
cylindrical  rollers,  and  feeding  them  with  the  blue,  through  small 
perforations  made  at  the  bottom  of  a  close  receptable  for  it,  placed 
immediately  over  the  upper  roller,  and  extending  the  whole  width 
of  the  calico,  to  which  the  colour  was  applied  before  it  could  have 
time  to  absorb  oxygene.  I  believe  this  invention  is  now  known  to 
others,  and  that  I  may  therefore  mention  it  without  any  breach  of 
confidence. 

t  1  cannot  discover  when,  or  by  whom,  orpiment  was  first  em- 
ployed to  promote  the  dissolution  of  indigo.  In  some  MSS.  with  the 
perusal  of  which  I  was  lately  favoured,  and  which  appear  to  have 
belonged  to  the  late  Dr.  Lewis,  author  of  the  Philosophical  Com- 
merce of  Arts,  and  to  contain  some  of  the  materials  employed  in  that 
work,  I  find  it  noted,  in  what  I  consider  as  the  Doctor's  hand- 
writing, and  under  the  date  of  1734,  that  certain  linen  printers 
(calico  being  then  but  little  employed  in  that  way)  had  offered  to 
give  him  one  hundred  guineas  if  he  could  "  find  out  a  way  to  print 
blue;"  and  that  the  writer  agreed  to  attempt  the  discovery,  if  these 
printers  would  make  him  acquainted  with  the  best  means  known 
to  themselves  of  doing  this,  which  they  did,  and  their  composition 
is  stated  to  have  consisted  of  equal  parts  of  indigo,  and  quick  lime, 
with  half  as  much  copperas,  (green  vitriol),  arid  twice  as  much 


Philosophy  of  Permanent  Colours.  157 

In  making  the  before-mentioned  composition,  a 
copper- coloured  pellicle  appears  on  the  surface  of  the 
liquor  as  soon  as  the  indigo  begins  to  dissolve;  and  this 
pellicle  becomes  violet,  and  at  last  blue,  by  longer  ex- 
posure to  the  atmosphere.  Mr.  Haussman  observes,  that 
the  same  pellicle  arises,  with  the  same  appearances,  if 
the  solution  of  indigo  be  put  into  contact  with  pure  vital 
air;  but  that,  under  the  receiver  of  a  pneumatic  machine, 
it  diminishes  in  proportion  as  a  vacuum  is  produced;  and 
that,  as  might  be  expected,  it  does  not  appear  at  all,  in 
either  hydrogene,  or  nitrogene.  He  farther  observes, 
that  if,  instead  of  orpiment,  the  sulphur  and  white 
arsenic,  of  which  it  is  formed,  be  employed,  together^ 
or  separately,  with  quick  lime  and  potash,  no  solution 
of  indigo  will  take  place;  and  this  will  also  happen,  even 
where  orpiment  is  used,  if  quick  lime  be  not  employed 
to  render  the  alkali  caustic.  That  having  put  indigo, 
dissolved  by  orpiment,  lime,  and  potash,  into  contact 
with  oxygene  gas,  obtained  by  distillation  from  nitre, 
he  soon  found  that  excepting  a  little  nitrogene  mixed 
with  it,  the  whole  had  been  absorbed  by  the  solution  of 
indigo,  and  the  blue  rendered  unfit  for  use,  the  indigo 
being  regenerated.  In  this  instance,  he  also  found  that 
a  part  of  the  alkali  remained  caustic,  while  another  part 
of  it  had  combined  with  the  vitriolic  (sulphuric)  acid, 

pearl  ash.  I  conclude  from  this,  that  the  use  of  orpiment,  for  the 
purpose  under  consideration,  was  then  unknown,  at  least  in  this 
country,  though  sulphate  of  iron  was  employed,  but  in  a  propof' 
tion  by  much  too  small  to  produce  its  beat  effect.  I  find  afterwards, 
an  account  of  several  experiments  made  by  the  writer,  to  accom- 
plish what  was  desired  of  him  by  the  linen  printers,  but  the  mcan^ 
Employed  by  him  for  this  purpose,  were  more  likely  to  impede, 
than  co-operate  in  the  dissolution  of  indigo.  So  little  was  the  subject 
then  understood,  that  all  reasoning  upon  it  tended  rather  to  mis- 
lead the  reasoner,  than  conduct  him  to  the  truth. 


158  Philosophy  of  Permanent  Colours, 

(formed  by  the  union  of  the  sulphur  to  a  part  of  the 
absorbed  oxygene)  and  thereby  produced  sulphate  of 
potash;  another  part  of  the  oxygene,  so  absorbed,  had 
combined  with  the  arsenic,  and  changed  its  metallic 
form  to  that  of  an  oxide,  in  which  state  it  had  united  to 
the  caustic  alkali;  and  the  rest  of  the  absorbed  oxy- 
gene had  combined  with,  and  regenerated  the  dissolved 
indigo. 

Mr.  Haussman  was  indeed  inclined  to  explain  the 
solution  of  indigo,  according  to  the  phlogistic  system, 
by  considering  it  as  resulting  from  a  greater  affinity 
which  phlogiston  was  supposed  to  have  with  indigo 
than  with  arsenic,  and  that  it  was  the  action  of  tliis 
phlogiston,  joined  to  that  of  the  caustic  alkali,  which 
operated  the  dissolution  in  question;  but  that  the  phlo- 
giston, having  still  a  greater  affinity  with  dephlogisti- 
cated  (or  vital)  air  than  with  indigo,  abandoned  the 
latter  as  soon  as  the  former  was  presented  to  it,  kaving 
the  indigo  in  its  regenerated  form;  the  alkali  alone  not 
being  sufficient  to  preserve  it  in  a  state  of  solution. 
But  a  much  happier,  and  more  natural  explanation  of 
these  effects,  is  affiDrded  by  the  new  doctrine,  as  already 
stated;  and  it  is  strongly  supported  by  all  that  we  know 
of  the  nature  of  indigo,  and  the  properties  of  those 
agents  which  are  employed  to  dissolve  it. 

Mr.  Haussman  found  that  the  sulphuret  of  antimony 
(crude  antimony)  assisted  in  dissolving  the  indigo,  for 
topical  blue,  as  well  as  orpiment,  but  that  it  was  unfit 
for  penciling  or  printing,  because  the  antimony  being 
precipitated,  in  the  form  of  a  mineral  kermes  or  golden 
sulphur,  tarnished  the  blue  colour,  and  adhered  to  the 
linens  or  cottons  almost  as  strongly  as  the  indigo  itself; 
an  inconvenience  which  I  have  also  experienced.  The 
oxide  of  antimony,  with  sulphur,  did  not  produce  a 
solution  of  the  indigo,  when  used  instead  of  the  crude 


Philosophy  of  Permanent  Colours.  159 

antimony;  though  antimony,  in  its  metallic  state,  (i.  e. 
the  regulus)  reduced  to  powder,  had  occasioned  the 
dissolution  of  indigo  in  the  same  way,  and  as  well  as 
the  crude  antimony.  He  found,  however,  that  no  such 
effect  was  produced  by  the  filings  of  zinc;  though  when 
heated,  this  metal  has  great  affinity  with  oxygene.  He 
attempted  in  vain,  to  dissolve  indigo,  by  a  combination 
of  sulphur  with  the  other  metals;  and  he  attributes  his 
want  of  success  to  the  circumstance  of  their  being  dis- 
solved with  difficulty,  or  perhaps  not  at  all,  "  par  la  voie 
humide,"  in  the  caustic  alkalies. 

Besides  repeating  a  great  part  of  these  experiments, 
and  with  nearly  similar  effiscts,  I  have  made  some, 
which,  probably,  were  not  attempted  before;  and  seve- 
ral of  them  produced  effects  highly  deserving  of  notice. 

Having  in  1791,  attempted  unsuccessfully  to  dissolve 
pure  blue  Guatamala  indigo,  finely  powdered,  by  long 
and  repeated  boilings  in  water,  with  an  excessive  pro- 
portion of  shell- lime  taken  hot  from  the  fire,  and  after- 
wards by  renewed  boilings  w^ith  a  copious  addition  of 
potash,  I  thought  it  might  be  worth  while  to  try  the 
oxide  of  tin,  which  had  then,  I  believe,  never  been 
employed  to  promote  the  dissolution  of  indigo.  It  so 
happened  that  I  had  at  hand  nearly  a  pound  of  an  oxide 
of  tin,  prepared  some  lime  before,  (for  a  different  pur- 
pose), by  putting  two  pounds  of  common  single  aqua 
fortis,  diluted  with  as  much  water,  upon  a  quantity  of 
tin,  not  in  very  small  pieces,  and  leaving  the  former  to 
act  slowly  upon  the  latter  during  several  months,  imtil 
all  its  oxygene  was  exhausted;  after  which,  I  found  the 
oxide,  or  calx,  formed  into  lumps,  and  settled  at  the 
bottom.  The  clear  liquor  being  decanted  from  the  oxide 
of  tin,  the  latter  was  slightly  rinced  with  water,  and  being 
dried,  remained  in  solid  lumps.  Some  of  these,  weigh- 
ing about  twice  as  much  as  the  indigo  which  I  had 


160  Philosophy  of  Permanent  Colours. 

found  it  impossible  to  dissolve,  by  the  means  just  men- 
tioned, were  put  into  the  caustic  alkaline  liquor,  and  in 
less  than  live  minutes  I  perceived  signs  of  a  beginning 
dissolution,  which  increased  rapidly,  until  the  liquor 
had  passed  through  all  the  shades  of  green,  and  become 
yellow,  except  at  its  surface,  which  was  covered  by  a 
fine  copper-coloured  pellicle,  of  a  shining  metallic  ap- 
pearance. Silk  and  cotton  dipped  into  the  liquor,  were 
taken  out  yellow,  but  quickly  became  green,  then  as- 
sumed a  shining  copper-colour,  which  afterwards  chang- 
ed to  violet,  and  finally  to  a  deep  bluej  which  was  found, 
by  washing,  to  be  permanently  dyed.  Part  of  the  same 
liquor,  gummed,  and  applied  topically,  answered  as 
well  for  penciling  as  any  topical  blue  I  ever  saw.  Ano- 
ther part  of  it,  being  poured  into  a  white  glass  phial,  so 
as,  with  a  portion  of  the  lime  and  oxide  of  tin,  to  fill  it 
completely,  (without  gum),  and  being  well  stopped  and 
left  at  rest,  the  mixture  in  a  few  days  became  as  pellucid 
and  colourless  as  clean  water^  excepting  only  the  sedi- 
ment at  bottom.*  Upon  unstopping  the  phial,  the  sur- 
face of  the  liquor,  by  coming  into  contact  with  the, 
atmosphere,  and  absorbing  oxygene,  instantly  became 
first  green,  and  then  blue;  and  upon  re-stopping  the 
phial,  and  shaking  it,  the  indigo  forming  this  blue  sur- 
face was  dispersed  through  the  mass  of  liquor,  and 
tinged  it  of  a  beautiful  greenish  yellow;  but  there  being 

*  I  have,  at  p.  126,  stated  the  basis  of  indigo  to  be  colourless^ 
when  ivhoUy  deprived  of  oxygene,  and  of  this,  the  fact"  just  mention- 
ed is  a  sufficient  proof.  Dr.  Roxburgh  has  indeed  said,  p.  287,  that 
"  the  indigo  base  is  naturally  green^  while  it  remains  dissolved  io 
its  watery  menstruum,  by  which  it  was  extracted  from  the  leaves.'* 
In  regard  to  this,  however,  I  will  only  observe,  that  ivherever  the 
basis  of  indigo  exhibits  a  green  colour,  it  must  be  combined  with  a 
portion  of  oxygene,  and  this  portion  must  be  greater  than  that  with 
which  it  is  united  in  the  yellow  solution  made  for  giving  blue  by 
to/deal  application. 


Philosophy  of  Permanent  Colours,  161 

a  sufficient  quantity  of  oxide  of  tin  unsaturated,  the 
oxygene  was  soon  absorbed,  and  the  liquor  again  ren- 
dered colourless.* 

When,  instead  of  the  oxide  of  tin,  I  employed  the 
metal  finely  granulated,  it  produced  no  effect  towards 
dissolving  indigo;  and  on  trying  tin,  which  had  been 
calcined  with  saltpetre  in  a  crucible,  I  found  that  it  not 
only  did  not  dissolve  the  indigo  itself,  but  prevented  it 
from  being  dissolved  by  the  oxide  of  tin  (produced  by 
the  aqua  fortis,  as  just  mentioned,)  or  by  crude  anti- 
mony, or  sulphate  of  iron,  either  singly  or  combined; 
indeed  it  was  with  difficulty  dissolved,  when  orpiment, 
in  a  large  proportion,  was  added  afterwards;  this  I  also 
found  to  be  the  case  of  tin,  calcined  alone  in  a  crucible 
by  strong  heat:  bismuth  calcined  in  like  manner,  equal- 
ly obstructed  the  solution  of  indigo.  Probably  in  these 
cases  the  metals  so  calcined  not  only  did  not  attract 
the  oxygene  of  indigo,  but  let  go  some  of  that  which 
they  had  imbibed  during  calcination. 

In  the  course  of  my  experiments  upon  indigo,  I  was 
induced  to  make  trial  of  a  large  proportion  of  refined 
sugar,  (instead  of  orpiment),  and  I  found  that  it  acted 
efficaciously  in  dissolving  indigo,  with  the  usual  ap- 
pearances, and  producing  a  topical  substantive  blue,  as 
permanent,  and  every  way  as  good  as  any  in  use.  I 
afterwards  tried  coarse  brown  sugar,  and  I  found  it  at 
least  as  effectual  as  the  refined,  for  this  purpose;  it  then 
occurred  to  me,  that  this  might  be  a  valuable  substitute 

*  Berthollet,  torn.  ii.  p.  57,  after  mentioning  my  discovery  of  the 
use  of  the  oxide  of  tin  in  promoting  the  dissolution  of  indigo,  adds, 
"  On  peut  dissoudre  immediatement  Tetain  peu  oxide,  dans  la 
potasse,  et  faire  agir  cette  dissolution  sur  Tindigo:  elle  produit 
promptment  une  cuve  ou  les  toiles  se  teignent  en  bleu  tree  intense'* 
The  formation  of  such  a  vat  was  naturally  suggested,  by  the  kaow- 
ledge  of  what  I  had  published  on  the  subject. 
V©L.I.  X 


162  Philosophy  of  Permanent  Colours. 

for  orpiment,  the  use  of  which,  as  a  constituent  part  of 
the  topical  blue,  may,  from  its  poisonous  quality,  some- 
times produce  mischief,  and  always  gives  the  compo- 
sition an  unpleasant  smell.  I  moreover  conceived,  that, 
by  employing  a  large  proportion  of  brown  sugar,  it 
might  be  practicable  to  thicken  the  mixture  sufficiently 
for  penciling  or  printing,  and  thereby  avoid  the  greater 
expense  of  gum  for  that  purpose;  and  upon  trial,  this 
also  proved  to  be  the  case,  the  sugar  thickening  the 
solution  sufficiently,  and  afterwards  drying  as  expedi- 
tiously as  when  thickened  by  gum,  contrary  to  what  I 
had  apprehended  as  probable,  from  recollecting  that 
ink,  vi^hen  thickened  by  sugar,  was  disposed  to  retain 
moisture,  and  dry  very  slowly.  I  think,  moreover,  that 
when  the  solution  of  indigo  is  both  made  and  thickened 
by  brown  sugar,  in  this  large  proportion,  the  latter,  by 
being  able  to  absorb  a  larger  quantity  of  oxygene  from 
time  to  time,  enables  the  topical  blue  to  bear  exposure 
to  the  atmosphere  somewhat  longer,  without  a  regene- 
ration of  the  indigo,  than  when  it  is  dissolved  by  only 
the  usual  proportion  of  orpiment.  I  conclude,  therefore, 
that  this  way  of  composing  a  substantial  topical  blue, 
by  employing  coarse  brown  sugar  instead  of  orpiment 
and  gum,  is  deserving  of  particular  attention,  as  form- 
ing a  composition  free  from  all  poisonous  qualities,  and 
at  the  same  time  cheaper  and  better  than  that  generally 
used.  Molasses  will  serve  as  well  as  brown  sugar  to 
promote  the  dissolution  of  indigo;  but  I  think  not  so 
well  to  supply  the  place  of  gum  in  thickening  the  com- 
position,* 

*  Since  the  former  edition  of  this  volume,  I  find  that,  according 
to  Professor  Pallas,  the  blue  dyers  of  Astracan  dissolve  indigo,  by 
boiling  it  in  a  lixivium  of  soda,  with  quick-lime  and  clarified 
honey;  which  last  appears  to  act  like  sugar  in  the  deoxygenation 
of  indigo.  Dried  raisins  and  figs,  I  have  observed  to  produce  a 


Philosophy  of  Permanent  Colours.  163 

Sugar  used  in  this  way,  seems  to  act  like  orpiment 
in  combining  with  cxygene;  which  it  is  strongly  dis- 
posed to  do  in  other  circumstances.  M.  Berthollet,  in 
the  second  volume  of  the  Annales  de  Chimie,  mentions, 
that,  in  distilling  the  sulphuric  acid  upon  different  ani- 
mal and  vegetable  substances,  he  found  none  of  them 
so  proper  as  sugar  to  form  a  large  quantity  of  sulphu- 
reous acid;  which  it  could  only  produce  by  its  great 
affinity  with  oxygene. 

I  found,  upon  different  trials,  that,  with  the  help  of 
potash  and  lime,  I  could  not  dissolve  indigo,  either  by 
sulphur,  or  white  arsenic,  or  charcoal,  or  oxide  of  bis- 
muth, or  of  lead  (minium),  or  of  zinc  (lapis  calaminaris,) 
or  of  manganese,  or  the  alkaline  solution  of  flints,  or  of 
the  earth  of  alum,  or  by  magnesia.  I  was  equally  unsuc- 
cessful with  copper,  in  all  the  ordinary  preparations  of  it: 
and  indeed  when  verdigrise  was  added  to  indigo  mixed 
with  lime  and  potash  as  usual, — there  was  not  only  no 
solution,  but  the  verdigrise  afterwards  obstructed  the 
action  of  all  other  agents  upon  it,  insomuch  that  the 

similar  effect.  Probably  the  most  useful  and  inoffensive  topical 
blue  may  be  made  by  boiling;  powdered  indigo  with  three  times  its 
weight  of  coarse  brown  sugar,  in  a  caustic  lixivium  of  soda  and 
potash,  and  assisting  the  deoxygenation  by  adding  the  oxide  of  tin 
precipitated  by  lime  from  a  solution  of  that  metal  by  muriatic  acid. 
If  a  muriate  of  tin  be  added  to  the  topical  blue,  prepared  with 
caustic  alkali  and  red  orpiment,  or  with  caustic  alkali  and  sugar, 
it  will  occasion  a  considerable  effervescence,  and  at  the  same  time 
produce  a  farther  deoxygenation  of  the  indigo,  and  thereby  render 
the  previous  greenish  yeiloiv  colour  of  the  mixture  almost  white, 
and  make  the  effervescing  froth  appear  almost  of  the  colour  of 
milk,  though  even  this  froth,  if  speedily  applied  to  calico,  will  at- 
tach itself,  and  by  regaining  oxygene,  stain  it  with  a  permanent 
blue  colour.  Such  an  effervescence,  however,  is  inconvenient,  and 
I  only  mention  the  fact  as  an  additional  illustration  of  the  theory 
before  stated. 


164  Philosophy  of  Permanent  Colours, 

indigo  remained  undissolved,  notwithstanding  the  com- 
bined action  of  crude  antimony,  orpiment,  oxide  of  tin, 
sulphate  of  iron,  and  sugar,  which  were  added  in  large 
doses,  any  one  of  which,  with  the  quick-lime  and  pot- 
ash, would  have  eftectually  dissolved  the  indigo,  had 
there  been  no  verdigrise  or  oxide  of  copper  in  contact 
with  it.  The  sulphate  of  zinc  (white  vitriol)  was  almost 
as  adverse  to  the  dissolution  of  indigo;  for  it  not  only 
did  not  contribute  thereto,  with  potash  and  lime,  but 
it  hindered  a  solution  from  taking  place,  by  the  oxide 
of  tin,  crude  antimony,  sugar,  and  sulphate  of  iron,  ap- 
plied one  after  the  other:  though  when  to  all  these,  a 
large  portion  of  orpiment  vvas  added,  and  the  mixture 
kept  some  time  in  a  boiling  heat,  the  indigo  did  at 
length  dissolve,  but  with  great  difficulty  and  tardiness. 
The  red  sulphuret  of  mercury  I  found,  on  repeated 
trials,  incapable  of  contributing,  in  any  degree,  to  dis- 
solve indigo  with  lime  and  potash;  though  it  did  not 
obstruct  the  dissolution  thereof,  when  orpiment  was 
added. 

Wishing  to  know  what  effects  would  result  from  a 
stronger  action  of  potash,  lime,  and  orpiment,  upon  indi- 
go, I  dissolved  it  with  three  times  the  usual  portion  of 
these  agents,  and  having  afterwards  shaken  the  whole 
mixture  well  together,  I  filled  a  large  transparent  glass 
phial  therewith  (but  without  any  gum,)  and  having  secur- 
ed it  from  all  contact  with  external  air,  by  a  glass  stopper 
covered  with  wax,  I  left  it  in  that  state  for  three  months, 
shaking  the  phial  occasionally,  that  the  more  fluid  part 
of  the  mixture  (which  had  become  colourless)  might 
be  acted  upon  more  equally  by  the  lime,  &c.  at  bottom; 
after  which,  the  phial  being  opened,  I  found  that  the 
mixture  (which  with  different  proportions,  had  always 
given  a  deep  permanent  blue  to  cotton,)  was  become 
incapable  of  manifesting  any  colour  by  the  contact  of 


Philosophy  of  Permanent  Colours.  165 

atmospheric  air;  the  indigo  having  been  not  only  de- 
prived of  the  oxygene  necessary  to  its  colour,  but 
probably  rendered  incapable  of  re-uniting  v/ith  it  as 
formerly,  in  consequence  of  a  decomposition  of  its 
vegetable  basis,  or  a  new  combination  thereof,  with 
one  or  more  of  the  agents  in  question,  too  intimate  to 
be  overcome  by  any  of  the  usual  means  of  regenerating 
indigo.  Here  we  have  an  instance  of  one  of  the  most 
permanent  of  colouring  matters  losing  its  colour  irreco- 
verably; not  by  any  thing  like  combustion,  which  neces- 
sarily requires  the  presence  and  combination  of  vital 
air,  but  by  means  which  seclude  it  from,  and  deprive  it 
of,  all  such  air. 

The  topical  blue,  when  made,  is  often  applied  by  the 
pencil  upon  spots  or  figures  previously  dyed  yellow,  in 
order  to  produce  a  permanent  green:  but  the  caustic 
alkali  contained  in  it,  especially  when  employed  too 
freely,  seems  to  weaken  the  yellow  on  wdiich  it  is  laid. 
Wishing  to  remove  this  difficulty,  I  thought  of  neutra- 
lizing the  alkali,  at  least  in  some  degree,  so  as  to  make 
it  harmless  in  this  respect,  without,  at  the  same  time, 
rendering  the  blue  less  efficacious.  For  this  purpose  I 
selected  the  muriatic  acid  principally,  because  as  no 
oxygene  had  ever  been  ascertained  to  exist,  as  one  of 
its  constituent  principles,  there  seemed  to  be  no  danger 
of  its  reviving  the  indigo,  by  imparting  oxygene  to  the 
topical  blue  when  mixed  with  it:  and  having  made  this 
mixture,  the  effi^ct  answered  my  expectation;  for  though 
it  produced  some  effervescence,  it  neither  rendered  the 
mixture  blue,  nor  even  its  effervescing  surface,  though 
covered  with  froth;  but  both  remained  green,  while  se- 
cluded from  the  contact  of  atmospheric  air,  by  being- 
inclosed  in  a  vessel  well  stopped;  and  I  found  it  practi- 
cable in  this  way  to  neutralize  the  alkali  completely, 
without  rendering  the  indigo  unfit  to  produce  a  fast 


166  Philosophy  of  Permanent  Colours. 

blue  colour,  or  a  green,  when  applied  to  yellows,  if 
applied  quickly;  but  when  the  topical  blue,  thus  neu- 
tralized, had  been  kept  some  time,  the  indigo,  being 
deprived  of  the  alkali  which  had  Iield  it  in  solution, 
gradually  subsided  in  a  great  degree,  and  became  unfit 
to  be  applied  topically.  There  is,  however,  I  think,  an 
intermediate  degree  to  which  the  alkali  may  be  neutra- 
lized, without  precipitating  the  indigo,  in  any  conside- 
rable quantity,  at  least  for  several  weeks,  and  whieli 
will  be  sufficient  to  prevent  the  alkali  from  exercising 
any  action  injurious  to  the  yellow  colours  upon  which 
the  blue  may  be  laid. 

The  fluoric  acid  employed  in  this  way  answered  as 
well  as  the  muriatic;  and  I  now  find  this  to  be  true  of 
the  sulphuric  and  some  other  acids;  there  being  no 
danger,  as  from  some  former  inaccurate  experiments  I 
had  once  supposed,  of  a  revival  of  the  indigo,  by  mix- 
ing either  of  them  with  the  topical  blue,  the  attraction 
of  the  basis  of  indigo  (in  this  preparation)  for  oxygene 
not  being  sufficient  to  decompose  any  of  these  acids,  so 
far  as  I  know.  Carbonic  acid  is  always  present  in  the 
topical  blue  without  being  decomposed;  and  no  injury 
is  produced  by  other  acids  when  mixed  with  it,  so  long 
as,  by  not  being  decomposed,  they  are  incapable  of  re- 
viving the  indigo.  I  have  ascertained  also  that  the  oxy- 
genated muriatic  acid  will  not  revive  it;  a  fact  which  I 
once  thought  favourable  to  the  opinion  of  Scheele  and 
Davy,  that  it  contains  no  oxygene;  but  the  other  facts 
just  stated,  show  that  nothing  decisive  in  that  respect 
can  be  inferred  from  it. 

It  is  to  be  observed  that  all  the  preceding  means  of 
rendering  indigo  soluble,  by  abstracting  a  part  of  its 
oxygene,  serve  only  to  bring  it  back  to  the  state  in 
which  it  existed  while  dissolved,  and  retaining  its  green 
colour  in  the  fermenting  process,  before  its  minutest 


Philosophy  of  Permanent  Colours,  167 

particles  had  been  collected  together,  in  a  concrete  blue 
form,  by  agitation;  and  I  have  already  mentioned,  at  p. 
126,  my  persuasion,  that  the  colouring  matter  of  the 
indigo  plant,  in  this  fluid  state,  is  not  only  fit  for  dyeing, 
but  that  the  blue  colour  dyed  with  it,  would,  like  that 
of  the  isatis,  or  woad,  prove  more  permanent  than  that 
given  by  the  indigo,  after  it  has  been  made  to  assume  a 
concrete  form;  because  its  basis,  even  by  the  least  hurt- 
ful ways  of  dissolving  it,  will,  I  think,  necessarily  be  in 
some  degree  weakened,  as  all  other  vegetable  colours 
are  found  to  be,  by  the  action  of  such  powerful  agents 
as  are  requisite  for  that  purpose;  and  I  think  it  proba- 
ble, that  the  very  durable  blues  which  are  given  by 
particular  people  in  some  parts  of  Africa,  owe  their 
superiority  to  this  method  of  dyeing. 

According  to  Mr.  Clarkson,  "it  is  well  known,  at 
least  in  the  manufacturing  towns,  that  the  African  dyes 
are  superior  to  those  of  any  other  part  of  the  globe.'* 
'*  The  blue  (continues  he)  is  so  much  more  beautiful 
and  permanent  than  that  which  is  extracted  from  the 
same  plant  in  other  parts,  that  many  have  been  led  to 
doubt  whether  the  African  cloths  brought  into  this 
country  were  dyed  with  indigo  or  not.  They  appre- 
hended that  the  colours  in  these,  which  became  more 
beautiful  upon  washing,  must  have  proceeded  from  ano- 
ther weed,  or  have  been  an  extraction  from  some  of  the 
woods  which  are  celebrated  for  dyeing  there.  The  mat- 
ter, however,  has  been  clearly  ascertained:  a  gentleman 
procured  two  or  three  of  the  balls,  which  had  been  just 
prepared  by  the  Africans  for  use:  he  brought  them  home, 
and  upon  examination  found  them  to  be  the  leavxs  of 
indigo  rolled  up  in  a  very  simple  state." 


163  Philosophy  of  Permanent  Colours. 

Sulphate  of  Indigo. 

The  powerful  action  of  sulphuric  acid  upon  indigo, 
and  the  very  bright  lively  blue  Colour  thereby  produced, 
had  been  observed  by  chemists  long  ago,  but  no  person 
seems  to  have  applied  this  colour  upon  cloth  as  a  dye, 
until  about  the  year  1 740,  when  it  was  done  by  Coun- 
sellor Barth,  at  Grossenhayn,  in  Saxony^  In  addition  to 
the  indigo  and  sulphuric  acid,  he  employed  crude  anti- 
mony and  lapis  caliminaris,  (and  as  some  say,  alum), 
mixing  them  with  the  oil  of  vitriol  first,  and  adding  the 
indigo  afterwards:  but  these  additions  being  found  use- 
less, were  after  some  time  discontinued. 

When  a  bit  of  pure  flora,  or  blue  Guatamala  indigo, 
is  dropped  into  concentrated  colourless  oil  of  vitriol,  in 
a  flint  glass  phial,  radiations  of  a  bright  greenish  yellow 
may  be  seen  almost  immediately  projecting  from  the 
indigo,  and  resulting  from  a  solution  begun  upon  its 
surface;  and  if  the  phial  be  left  unagitated,  these  radia- 
tions soon  become  green,  and  afterwards  blue,  without 
any  motion  or  change  in  their  direction.  This  sudden 
conversion  of  the  blue  colour  of  the  indigo  to  a  green- 
ish yellow,  seemed  to  indicate  an  abstraction  of  oxygene, 
as  its  cause;  but  it  was  difficult  to  conceive  how  such 
an  abstraction  could  result  from  the  application  of  an 
acid,  already  completely  saturated  with  oxygene.  I  re- 
collected, however,  that  Berthollet  had  mentioned,  as 
one  of  the  effects  caused  by  the  action  of  sulphuric  acid 
upon  indigo,  that,  of  its  determining  (as  it  does  with 
sugar)  the  production  of  a  little  water,  in  consequence 
of  the  intimate  combination  which  it  effects  between 
certain  portions  of  the  oxygene  and  hydrogene,  which 
are  among  the  constituent  parts  of  indigo;  a  combina- 
tion by  which  he  accounts  for  the  great  heat,  resulting 
from  a  mixture  of  powdered  indigo  with  sulphuric  acid, 


Philosophy  of  Permanent  Colours.  169 

and  the  non  production  oi  sulphureous  acid  thereby.  This 
feet,  of  the  production  of  water  by  a  combination  of  a 
part  of  the  oxygene  of  the  indigo,  with  a  part  of  its  hy- 
drogene,  enables  us  to  understand  how  the  indigo  may, 
and,  indeed,  must  be  deprived  of  a  portion  of  oxygene, 
sufficient  to  change  its  colour,  suddenly,  to  a  greenish 
yellow;  and  this  change  being  effected,  the  progress  af- 
terwards, to  green  and  blue,  accords  with  the  series  of 
changes  observed  in  the  topical  blue  of  the  calico  print- 
ers, after  its  application;  and  indicates  a  restitution  of 
the  oxygene,  taken  from  the  indigo  by  the  formation  of 
water.  To  ascertain  with  certainty  whence  this  restitu- 
tion was  made,  or  rather  whether  any  part  of  it  was  de- 
rived from  the  atmosphere,  I  placed  a  small  piece  of  the 
Guatamala  indigo  in  a  phial,  and  filling  it  completely 
with  colourless  oil  of  vitriol,  I  closed  it  immediately 
with  its  ground  glass  stopper,  which  came  in  contact 
with  the  acid  and  indigo,  (the  latter  from  its  levity  rising 
to  the  top)  so  as  to  leave  no  space  for  air.  I  then  placed 
the  phial  at  the  window,  and  keeping  it  motionless,  saw, 
by  transmitted  light,  streaks  of  greenish  yellow  radiating 
downward  from  the  indigo,  and  gradually  changing  and 
passing  through  all  the  intermediate  shades  of  green,  to 
a  full  sky  blue;  and  as  nothing  could  have  been  gained 
from  the  atmosphere  during  these  changes,  it  was  ma- 
nifest that  they  must  have  been  produced  by  something 
contained  in  the  sulphuric  acid;  and  as  the  latter  does 
not  appear  in  this  operation  to  suffer  any  decomposition, 
nor  the  indigo  to  be  capable  of  effecting  any,  I  conclude, 
that  when  this  last  has  been  rendered  soluble,  by  the 
deoxygenation  resulting  from  a  production  of  water,  it 
enters  into  a  triple  combination  with  the  oxygene  and 
sulphur  composing  the  acid,  and  thereby  regains  its 
blue  colour,  with  additional  brightness;  cither  from  its 
union  with  an  increased  proportion  of  oxygene,  or  from 
Vol.  L  Y 


170  Philosophy  of  Permanent  Colours. 

some  efFect  resulting  from  the  sulphur,  which  had  not 
been  combined  with  it  originally.  But  though  the  co- 
lour is  rendered  much  more  beautiful  by  this  triple 
combination,  it  is  accompanied  with  a  great  diminution 
of  its  former  stability,  and  differs  essentially  from  the 
solutions  of  indigo  made  by  lime  and  alkalies,  assisted 
by  the  deoxygenating  agents  lately  mentioned;  for  when 
indigo  is  revived  or  recovered  after  the  latter  mode  of 
solution,  it  is  found  to  possess  all  the  properties  which 
belonged  to  it  before  it  had  undergone  any  solution,  in- 
cluding its  original  indissolubility,  (except  by  the  agents 
already  mentioned.)  But  after  being  dissolved  by  sul- 
phuric acid,  it  can  never  be  revived  with  its  original 
and  peculiar  properties.  It  may,  indeed,  be  readily  pre- 
cipitated by  alkalies,  but  excepting  a  blue  colour,  the 
precipitate  will  differ  from  indigo  in  every  respect.  It 
will  no  longer  retain  the  power  of  emitting  its  charac- 
teristic purple  smoke^  when  ignited;  and  it  may  be  rea- 
dily dissolved,  by  all  the  acids,  and  alkalies,  as  well  as 
by  other  agents  which  previously  had  no  dissolving 
power  over  it;  and,  though  most  of  these  solutions  are 
blue,  their  colour  has  but  little  permanency,  especially 
those  made  with  pure  alkalies,  whether  fixed  or  volatile, 
as  they  soon  spontaneously  become  green,  and  finally 
colourless. 

When  the  basis  of  indigo,  after  being  sufficiently 
deoxygenated,  is  dissolved  by  lime  or  alkalies,  it  forms 
no  permanent  combination  with  either,  and  may  after- 
wards be  separated  and  recovered  from  them  without 
having  suffered  any  perceptible  injury  or  change.  But 
the  effect  is  very  different  after  this  basis  has  been  dis- 
solved by  any  of  the  acids;  probably  it  suffers  least  in- 
jury from  the  sulphuric,  though  with  this,  indigo  can 
hardly  be  said  to  produce  a  fast  colour,  even  on  wool, 
since,  as  Haussman  observes,  it  is  easily  extracted  by 


Philosophy  of  Permanent  Colours.  171 

soap  J^i  boiling  water,  and  changed  by  alkalies  to  an 
olive  colour,  more  or  less  yellow,  according  as  the  al- 
kali is  more  or  less  caustic;  and  since  the  adhesion  of 
this  blue  to  linen  and  cotton  is  so  feeble,  that  cold  rui\- 
ning  water  will  gradually  carry  it  off. 

Bergman,  (whose  labours  have  thrown  much  light  on 
the  subject  of  indigo)  ascribes  the  want  of  greater  per- 
manency in  the  Saxon  blue,  to  the  use  of  sulphuric 
acid,  not  sufficiently  concentrated.  He  used  an  acid 
whose  specific  gravity,  compared  to  that  of  water,  was 
as  1900  to  1000,  and  employed  eight  pounds  of  this 
acid,  to  dissolve  one  pound  of  indigo.  I  believe,  how- 
ever, that  he  was  misled  on  this  subject,  and  that  Pcier- 
ner  is  much  nearer  the  truth,  when  he  says,  that  the 
best  proportion  for  dissolving  indigo,  is  only  four  times 
its  weight  of  good  pure  oil  of  vitriol;  and  that  where 
more  is  used,  the  blue  is  less  permanent.  I  am  even 
inclined  to  think  that  the  blue  will  prove  more  durable, 
if  this  last  quantity  of  acid  be  diluted,  with  an  equal 
portion  of  hot  water,  as  soon  as  the  indigo  is  put  to  it, 
and  the  mixture  left  in  a  warm  situation  48  instead  of 
24  hours,  for  the  indigo  to  dissolve;  because,  by  a 
slower,  and  more  moderate  action,  I  think  the  basis  of 
the  indigo  will  be  less  weakened;  at  least  I  have  fre- 
quently dissolved  indigo  in  this  way,  and  the  colour 
has  appeared  to  be  more  durable,  than  when  it  was  dis- 
solved by  an  undiluted  acid.*  The  indigo  being  dissolv- 
ed, Mr.  Poerner  adds  as  many  ounces  of  dried  potash, 
as  there  were  of  indigo  in  the  solution,  which  produces 
an  effervescence;  and  after  twenty-four  hours,  he  adds 
eight  pounds  and  a  half  of  water,  for  each  pound  of  oil 
of  vitriol  employed,  and  puts  the  whole  into  a  glass 

*  If  the  indigo  be  Jinely  fioivdered^  it  will  be  thereby  rendered 
soluble,  with  a  smaller  proportion  of  the  acid,  and  even  that  pro- 
portion may  be  more  diluted. 


172  Philosophy  of  Permanent  Colours. 

vessel  for  use.*  Instead  of  potash,  I  have  used  clean 
chalk,  and  this  even  in  such  quantities,  as  to  saturate 
the  vitriolic  acid.    The  indigo  was  then  precipitated 
with  the  chalk,  and  being  collected  in  a  solid  mass,  it 
was  still  capable  of  dyeing  a  blue  on  wool,  though  it 
took  much  more  slowly  than  in  the  ordinary  way  of 
dyeing  Saxon  blue;  in  which  the  colour  applies  itself  so 
rapidly  to  wool  or  woUen  cloth,  as  to  render  it  difficult 
to  prevent  its  taking  unequally,  a  defect  which  might 
probably  be  obviated  by  a  small  portion  of  chalk.  It  is 
to  prevent  this  inequality,  that  M.  d'Ambourney  ad- 
vises, where  deep  Saxon  blues  are  wanted,  to  pass  the 
cloth  at  different  times  through  vessels  containing  only 
what  might  suffice  for  weak  colours,  in  order  that  the 
blue  may,  by  these  partial  applications,  be  made  to  take 
with  more  evenness.  Silk,  dyed  along  with  wool,  takes 
a  much  weaker  colour,  (I  mean  with  the  addition  of 
chalk),  because  it  has  less  affinity  with  the  indigo  than 
wool  has.  This  preparation  of  indigo,  however,  would 
not  give  a  deep  blue,  because  being  united  with  so 
large  a  portion  of  white  sulphate  of  lime,  the  blue  co- 
louring particles  could  not  be  sufficiently  condensed  for 
that  purpose.  Pcerner  conceives  the  Saxon  blue  to  be 
rendered  more  durable   by  previously  preparing  the 
cloth  with  alum,  and  sulphate  of  lime. 

The  solution  of  indigo  by  sulphuric  acid,  is  usually 
called  by  dyers  chemical  blue.  It  ought,  however,  ac- 
cording to  the  new  nomenclature,  to  be  termed  sulphate 
of  indigo;  a  name  by  which  I  shall  continue  to  distin- 

*  Poerner  says,  and  I  think  truly,  that  by  this  addition  of  potash, 
a  more  agreeable  blue  is  produced,  and  that  it  penetrates  farther 
into  the  cloth.  He  mentions  as  an  instance  of  the  abundance  of 
colouring  matter  afforded  by  indigo,  his  having  dyed  five  pieces  of 
cloth,  each  weighing  one  pound,  of  different  shades  of  Saxon  blue, 
all  with  a  single  half  ounce  of  indigo. 


Philosophy  of  Permanent  Colours.  173 

guish  it.^  When  applied  to  wool,  the  blue  colour  is 
much  more  permanent  than  it  is  in  a  fluid  state;  for 
though  a  little  manganese,  added  to  the  sulphate  of  in- 
digo, instantly  destroys  its  colour, f  wool,  which  had 
been  previously  dyed  blue  with  some  of  the  same  pre- 
paration, was  not  discoloured  by  the  action  of  manga- 
nese, dissolved  in  sulphuric  acid. 

I  do  not  know  that  a  black  was  ever  produced  by  the 
sulphate  of  indigo,  or  by  any  other  preparation  of  that 
drug  alone.  Mr.  John  Wilson,  who  greatly  contributed 
to  improve  the  art  of  dyeing  at  Manchester,  has  asserted, 
that  though  a  redundance  of  colouring  matter  will  in- 
crease the  force  and  body  of  a  colour,  yet  that  no  repeat- 
ed dyeings  of  blue  will  become  black.  I  have,  however, 
now  before  me,  two  pieces  of  cloth,  one  of  which  is  the 
deepest  and  purest  black  perhaps  ever  seen,  and  it  was 
dyed  by  me,  very  lately,  from  sulphate  of  indigo,  em- 
ployed alone,  though  in  an  unusual  quantity;  the  other  is 

*  Poerner  describes  a  sulphate  of  indigo,  which  he  prepared  in  a 
dry  solid  form,  and  reserved  as  a  secret:  he  represents  it  as  being 
more  commodious,  and  advantageous  for  dyeing,  than  the  common 
sulphuric  solution  of  indigo.  Berthollet  conjectures  (tom.  ii.  p.  97) 
that  this  may  have  been  the  precipitate  which  I  had  recommended, 
of  sulphate  of  indigo,  by  an  addition  of  carbonate  of  lime.  It  doubt- 
less must  have  been  a  precipitate  by  this  or  other  means-. 

t  The  destructive  action  which  manganese  exerts  upon  the 
colour  of  indigo,  when  it  (i.  e.  the  manganese)  is  mixed  with  sul- 
phuric acid,  though  weaker,  resembles  that  of  muriatic  acid,  after 
it  has  been  mixed  with  manganese;  and  to  my  conception,  affords 
a  strong  presumption,  that  in  both  mixtures,  the  destroying  power 
depends  upon  a  co-operation  of  something  gained  from  the  manga- 
nese; which  is,  however,  contrary  to  the  notion  of  Scheele  and 
Davy,  that  muriatic  acid,  by  its  admixture  with  manganese,  and 
conversion  to  oxy muriatic  acid,  gains  nothings  but  is  merely  de- 
prived of  the  hydrogene  previously  combined  with  it;  and  that  this 
deprivation  constitutes  the  whole  difference  between  the  muriatic 
and  oxymuriatic  acids.  Manganese  added  to  the  topical  blue,  soon 
revives  the  indigo,  but  does  not  injure  it9  colour. 


174  Philosophy  of  Permanent  Colours, 

a  fine  Saxon  blue,  which  was  cut  off  from  the  first,  be- 
fore it  had  taken  up  so  much  of  the  blue  colour,  as  to 
become  black.  I  lately  found  also,  in  making  the  topical 
blue,  that  a  small  piece  of  cotton,  which  I  had  thrown 
into  the  mixture,  and  which,  being  forgotten,  had  re- 
mained there  forty-eight  hours,  was,  when  taken  out,  of 
2l  full  blacky  so  permanently  fixed,  that  neither  lemon 
juice  nor  alkalies  seemed  capable  of  impairing  it.  I  could 
not,  in  one  or  two  trials  afterwards,  succeed  in  producing 
a  similar  black  on  linen  or  cotton;  and  it  must  be  re- 
marked, that  when  I  produced  this,  it  was  in  a  mixture 
to  which  I  had  at  first  put  a  little  manganese,  to  see 
whether  it  would  promote  the  dissolution  of  indigo;  and 
finding  it  did  not,  I  had  aftenvards  added  more  than  the 
usual  proportion  of  orpiment;  one  or  both  of  which  addi- 
tions, may  have  contributed  to  the  black  in  question.* 

*  That  Saxon  blue,  or  the  colour  of  indigo,  in  combination 
with  sulphuric  acid,  depends  upon  the  union  of  a  certain  pro- 
portion of  oxygene,  as  in  all  other  preparations  of  this  drug,  may- 
be proved,  by  adding  to  the  sulphate  of  indigo,  a  little  muriate 
of  tin,  which  by  its  ordinary  deoxidating  influence  soon  changes 
the  blue,  first  to  green,  and  then  to  a  pure  bright  yellow.  If 
this  yellow  mixture  be  applied  to  linen  or  calico,  it  will  dry  with- 
out losing  its  yellow  colour,  the  affinities  of  the  oxide  of  tin,  or 
of  the  muriatic  acid,  or  of  both,  counterbalancing  that  of  the 
indigo  for  oxygene.  But  if  the  linen  or  calico  be  moistened  with  a 
weak  solution  of  carbonate  of  soda,  or  potash,  to  neutralize  the  acid, 
the  yellow  will  return  through  all  the  shades  of  green,  to  the  for- 
mer Saxon  blue.  Muriatic  acid  ivithout  tiny  produces  no  change  in 
the  colour  of  sulphate  of  indigo,  because  it  has  alone  no  deoxyge- 
nating  power.  Analogous  to  the  preceding  fact,  (now  first  men- 
tioned) is  that  published  by  Vauquelin,  of  the  deoxygenating 
influence  of  hydro-sulphurated  water,  which  when  mixed  in  a 
close  stopped  phial  with  sulphate  of  indigo,  soon  becomes  green, 
and  in  a  few  days  yellow;  but  if  the  phial  be  afterwards  unstopped, 
the  sulphate  of  indigo  gradually  returns  through  the  different 
shades  of  green  to  its  former  blue  colour,  as  fast  as  the  separation 
of  sulphuretted  hydrogene  permits  the  indigo  to  recover  its  oxy- 


Philosophy  of  Permanent  Colours.  175 

The  sulphuric  acid,  or  oil  of  vitriol,  as  commonly  pre- 
pared, contains  a  small  portion  of  the  nitric,  which,  how- 
ever small,  necessarily  does  some  harm  in  forming  the 
sulphate  of  indigo.  M.  Chaptal  observes,  that  he  has  seen 
the  colour  fail,  and  the  stuffs  intended  to  have  been  dyed 
spoiled  by  this  fault  in  the  sulphuric  acid  employed  for 
that  purpose,  which  ought,  therefore,  to^  be  guarded 
against  as  much  as  possible. 

The  indigo  of  all  others  most  preferred  for  Saxon 
blues,  is  the  flora  of  Guatamala,  which  indeed  is  seldom 
employed  for  any  other  species  of  blue. 

The  other  kinds,  when  mixed  with  oil  of  vitriol,  effer- 
vesce sometimes  very  strongly,  in  consequence  of  the 
extrication  of  fixed  air;  the  presence  of  which  may 
easily  be  accounted  for,  by  recollecting  that  lime  is  com- 
monly employed  to  accelerate  the  separation  and  precipi- 
tation of  the  minute  particles  of  indigo,  while  in  the 
vessels  called  beaters,  and  that  in  doing  this,  it  subsides 
with  the  indigo,  after  having  absorbed  carbonic  acid, 
which  in  this  way  is  again  set  free  by  the  oil  of  vitriol. 
Here  it  will  be  proper  that  I  should  offer  some  conjec- 
tures on  the  cause  of  the  different  colours  of  indigo:  and 
as  a  foundation  for  these,  I  must  remark,  that  the  flora, 
or  blue  indigo  of  Guatamala,  is  much  lighter  than  the 
violet,  and  that  this  last  is  lighter  than  the  copper-colour- 
ed. From  the  lightness  of  this  blue  indigo,  and  from  its 
not  effervescing  with  acids,  when  dissolved  by  oil  of 
vitriol,  there  is  the  strongest  reason  to  conclude  that  no 
lime  is  employed  to  accelerate  the  separation  and  precipi- 
tation of  its  colouring  matter  in  the  beaters;  since,  if 
there  had  been  any,  it  would  have  increased  the  specific 

gene.  An  undissolved  hydro-sulphuret  will  act  more  efficaciously 
in  this  way,  so  as  to  render  the  sulphate  of  indigo  almost  colour- 
less; after  which,  if  it  be  applied  to  calico,  the  latter  will  first  be- 
come yellow,  next  green,  and  then  blue. 


176  Philosophy  of  Permanent  Colours^ 

gravity  of  the  indigo,  and  by  absorbing  carbonic  acid, 
would  necessarily  have  caused  an  effervesence,  when 
dissolved  in  sulphuric  acid;  assuming,  therefore,  that  no 
lime  is  employed  to  separate  and  precipitate  the  colour- 
ing matter,  it  would  necessarily  follow,  that,  to  obtain 
such  separation  and  precipitation,  the  agitation  must  have 
been  continued  longer  than  would  otherwise  have  been 
necessary,  and  the  unavoidable  consequence  would  have 
been,  the  combination  of  a  larger  proportion  of  oxygene 
with  the  colouring  particles  so  exposed  to  it,  than  that 
which  takes  place  with  those  separated  by  lime:  it  will 
therefore  follow,  that  indigo,  obtained  in  this  way,  will 
contain  a  greater  portion  of  oxygene  than  in  the  other; 
and  it  seems  natural  to  conclude,  that  the  blue  colour  is 
occasioned  thereby.  To  ascertain,  however,  the  justice 
of  this  conclusion  as  far  as  I  was  able,  I  took  some  of 
the  lightest  and  bluest  Guatamala  indigo,  and  dissolved 
it  by  lime,  potash,  and  orpiment,  as  usual;  one  effect  of 
such  solution,  we  know  to  be,  the  taking  away  from  the 
indigo  a  considerable  part,  at  least,  of  its  oxygene;  and  I 
accordingly  found,  as  I  have  done  in  all  cases  where 
indigo  was  dissolved  for  the  topical  blue,  that  the  disso- 
lution was  accompanied  with  a  bright  shining  copper-co- 
loured pellicle  upon  the  surface  of  the  liquor,  which  of 
itself  was  of  a  greenish  yellow  underneath.  The  produc- 
tion of  this  pellicle  may  be  easily  explained  by  recollecting 
that  the  dissolved  indigo,  which  has  lost  its  oxygene,  and 
become  thereby  of  this  greenish  yellow,  being  at  its  sur- 
face in  immediate  contact  with  atmospheric  air,  regains 
a  part  of  what  it  had  lost,  and  by  doing  so,  becomes 
copper-coloured;  but  swimming  as  it  does  upon  a  mix- 
ture disposed  to  attract  oxygene,  it  cannot,  in  this  state, 
retain  so  much  thereof  as  the  indigo  itself  formerly  had, 
while  it  was  of  a  blue  colour;  and,  therefore,  so  long  as 
the  body  of  the  liquor  remains  yellow  or  green,  the  pelli- 


Philosophy  of  Permanent  Colours.  177 

ele  covering  it,  will  be  only  copper- coloured,  though 
consisting  of  a  colouring  matter  which  was  formerly 
blue,  and  which  would  have  become  so  again,  if,  being 
dissolved,  it  had  been  thinly  applied  to  linen  or  cotton, 
and  brought  sufficiendy  into  contact  with  the  oxygene  of 
the  atmosphere.  As  therefore  this  blue  indigo  had  appa- 
rently become  copper-coloured,  only  by  having  less 
oxygene  than  before,  is  there  not  from  this  circum- 
stance, an  additional  reason  to  conclude,  that  the  copper- 
coloured  indigo,  t^^eparated  and  precipitated  by  lime,  is 
made  of  that  colour,  only  by  its  possessing  a  smaller 
proportion  of  oxygene  than  the  blue  indigo?  and  whilst 
this  blue  indigo  is  preferred  for  combination  with  sulphu- 
ric acid,  as  producing  least  effervescence,  we  should 
expect  that  the  copper- coloured,  as  being  the  least  oxy- 
genated, would  be  most  suitable  for  the  indigo  vats,  and 
for  the  topical  blue,  because  in  these  the  dissolution  is 
effected  by  taking  away  oxygene;  and  the  less  there  is 
of  it,  the  more  easily  will  this  be  effected;  and  here  the 
choice  and  practice  of  the  dyers  accord  with  my  hypo- 
thesis, as  they  constantly  employ  the  copper- coloured 
indigo  for  these  last  purposes. 

Having  already  noticed  all  the  known  means  or  sol- 
vents by  which  indigo  can  be  rendered  useful  in  dyeing, 
I  will  only  add  a  few  observations  concerning  the  effects 
of  some  other  agents  upon  it. 

If  strong  nitric  acid  be  mixed  with  powdered  indigo, 
its  action  upon  the  hydrogene  of  the  latter  ^vill  be  so 
violent,  as  to  produce  actual  combustion;  and  when  di- 
luted, its  power,  though  moderated,  will  always  prove 
destructive  of  all  the  useful  properties  of  indigo,  unless 
it  be  made  so  weak,  as  to  manifest  no  sort  of  influence 
upon  it.  When  it  is  of  the  strength  of  common  or  single 
aqua  fortis,  it  dissipates  a  considerable  portion  of  the 
component  parts  of  the  indigo,  and  converts  the  remain- 

VOL.  I.  Z 


178  Philosophy  of  Permanoit  Colours. 

der  into  a  rusty  brown  viscous  bitter  mass,  which  will 
burn  and  detonate,  and  which,  according  to  Haussman, 
is  soluble  in  alcohol,  and  also  in  water,  when  the  pro- 
portion of  the  latter  is  very  large.  With  a  more  diluted 
nitric  acid,  the  indigo  at  first  afibrds  a  bright  yellow,  but 
it  soon  changes  to  die  rusty  brown  before  mentioned; 
and  the  basis  of  indigo  is  then  so  completely  decom- 
posed, that  the  blue  colour  cannot  be  restored,  by  any 
of  the  various  means  which  I  have  employed  for  that 
purpose. 

The  most  concentrated  muriatic  acid,  even  with  a 
boiling  heat,  has  no  action  upon  the  pure  colouring  mat- 
ter of  indigo,  though  it  dissolves  some  other  parts  of  it; 
and  this  is  true  of  the  citric,  tartaric,  acetic,  phosphoric, 
fluoric,  and  other  acids. 

A  mixture  of  sulphuric,  nitric,  and  muriatic  acids, 
greatly  diluted,  will  slowly  dissolve  powdered  indigo, 
and  change  its  colour  to  a  very  bright  lively  yellow, 
which  appears  to  have  considerable  stability,  though  it 
could  not  be  fixed  on  linen  or  cotton. 

It  is  remarkable  that  though  the  strongest  muriatic 
acid,  even  when  boiUng,  has  no  influence  upon  the  co- 
louring matter  of  indigo,  yet  this,  or  even  a  much  weaker 
acid,  when  it  has  been  saturated  by  dissolving  tin,  will, 
if  mixed  with  powdered  indigo,  in  the  common  tempera- 
ture  of  the  atmosphere,  speedily  make  it  green,  and 
afterwards  yellow;  holding  a  considerable  portion  of  it 
suspended  in  the  state  of  a  yellow  solution,  whilst  the 
residue  subsides,  as  a  powder  of  the  same  colour.  In  this 
case,  the  oxide  of  tin  first  produces  a  deoxygenation  of 
the  basis  of  indigo,  and  thereby  renders  it  soluble  by  the 
muriatic  acid,  to  which  it  was  before  inaccessible.  But 
being  so  dissolved,  this  basis  either  undergoes  a  decom- 
position, or  enters  into  a  new  combination  with  the  oxide 
of  tin,  or  the  muriatic  acid,  or  both,  of  a  nature  so  inti- 


Philosophy  of  Permanent  Colours,  179 

mate,  that  no  means  which  I  have  been  able  to  employ, 
to  remove  or  neutralize  the  acid,  have  enabled  the  indigo 
to  regain  its  former  portion  of  oxygene,  or  return  to  its 
former  blue  colour;  as  the  sulphate  of  indigo  will  do  by 
such  means,  when  it  has  been  made  yellow  by  muriate 
of  tin. 

The  insolubility  which  the  basis  of  indigo  acquires  by 
combining  with  oxygene,  may,  as  Berthollet  observes, 
be  compared  to  that  of  certain  metallic  oxides,  which  at 
a  maximum  of  oxidation,  cannot  be  dissolved  by  acids, 
but  are  made  soluble  by  the  application  of  means  suited 
to  produce  an  abstraction  of  oxygene.  And  here  I  may 
terminate  my  explanation  of  the  extraordinary  and  highly 
interesting  chemical  properties  of  indigo,  believing  that 
it  will  suffice  to  enable  my  readers  to  understand,  both 
the  reason  and  effects  of  the  several  methods  and  means 
employed  to  fix  its  colour,  by  dyeing  and  calico  print- 
ing. 

It  now  only  remains  for  me  to  mention  some  facts 
respecting  the  history  of  indigo,  which  have  been  pur- 
posely kept  back,  because  I  believed  they  would  be  read 
with  more  interest,  and  be  better  understood  when  the 
properties  of  this  drug  had  been  previously  made  known. 

Mr.  J.  N.  BischofF,  in  a  work  which  manifests  great 
reading  on  the  subject  of  dyeing,  ("  Versuche  einer  ges- 
chichte  der  Farberkunst,  1780,'')  appears  to  think,  that 
the  indigo  with  which  we  are  acquainted,  was  unknown 
to  the  Greeks  and  Romans;  that  the  indicum  of  Pliny 
was  not  a  dyeing  drug,  but  a  paint  very  different  from 
our  indigo;  and  that  the  charter  or  contract  which  passed 
in  1194,  between  the  cities  of  Bologna  and  Ferrara,  re- 
specting certain  duties  to  be  paid  at  the  former  city, 
upon  the  Grana  de  Brasile,  (or  Kermes),  and  upon  indi- 
go, alluded  to  the  indicum  of  Pliny,  and  not  to  the 
substance  now  called  indigo.  It  may,  however,  be  de« 


180  Philosophy  of  Permanent  Colours. 

monstrated  from  the  known  properties  of  our  indigo, 
and  those  which  Pliny  has  distinctly  mentioned  as  be- 
longing to  his  indicum,  that  the  former  is  an  exact 
resemblance  of  the  latter.  After  describing  the  prepara- 
tion of  a  very  costly  fine  purple  substance  employed  by 
painters,  (and  obtained  by  skimming  the  vessels  in 
which  the  Tyrian  purple  was  dyed,)  Pliny  mentions, 
(lib.  XXXV.  c.  6.)  the  indicum  as  next  in  value  and  im- 
portance. *'  Ab  hoc  maxima  autoritas  indico:  ex  India 
venit,"  &c. — "  cum  teritur  nigrum;  at  in  diluendo  mis- 
turam  purpuras  coeruleique  mirabilem  reddit."  After 
.this  mention  of  the  country  whence  it  was  obtained, 
and  of  the  admirable  mixture  of  blue  and  purple  co- 
lours which  it  exhibited  by  being  diluted,  he  adds, 
that  it  had  been  frequently  adulterated  by  pigeons' 
dung,  and  other  fraudulent  mixtures;  and  then,  with 
great  sagacity,  he  points  out  a  trial  by  which  the  ge- 
nuine drug  might  always,  and  certainly^  be  distinguish- 
ed  from  the  spurious;  and  this  was  by  putting  it  upon 
live  coals;  where,  says  he,  the  true  indicum  will  burn 
with  aflame  of  the  most  beautiful  purple  tint,  "  Proba- 
tur  carbone:  reddit  enim,  quod  sincerum  fiammam  ex- 
cellentis  purpura.'*'^  I  have  already,  at  p.  145,  mentioned 
this  purple  flame,  and  the  purple  smoke  accompanying 
it,  as  peculiarly  distinguishing  indigo.  It  was  a  criterion 
abundantly  sufficient  for  Pliny's  purpose,  and  the  only 
one^  which,  in  the  then  deplorable  state  of  chemical 
science,  could  have  been  suggested  by  him.  It  is  true 
that  the  Greeks  and  Romans,  not  knowing  how  to  dis- 
solve indigo,  used  it  only  in  painting,  but  their  igno- 
rance did  not  alter  its  nature,  or  hinder  it  from  being, 
as  it  must  have  been,  the  identical  substance,  with  the 
uses  and  properties  of  which  we  are  now  so  much  bet- 
ter acquainted.  It  is  true,  also,  that  Pliny  was  mistaken, 
not  in  regard  to  the  place  whence  it  came,  but  in  regard 


Philosophy  of  Permanent  Colours-  181 

to  the  way  in  which  it  was  produced;  he  having  sup- 
posed it  to  be  a  slime  naturally  collected  in  the  scum 
of  the  sea,  and  adhering  to  certain  reeds  growing  on  its 
shores  (*'  harundinum  spumae  adhaerescente  limo"). 
And  with  this  notion,  he  imagined  that  the  peculiar 
odour  of  indigo,  when  burning,  resembled  the  smell  of 
the  ocean,  a  circumstance  which  he  says  made  some 
think  it  was  gathered  from  the  rocks  ("  dum  fumat, 
odorem  maris  olet:  ob  id  quidam  e  scopulis  id  colligi 
putant.")  These  notions,  and  the  different  names  and 
circumstances  which  were  applied  to  this  substance,  or 
mentioned  as  connected  with  it,  by  Dioscorides,  Galen, 
Paulus  iEgineta,  and  others,  induced  Caneparius,  in 
his  work  "  de  Atramentis,  &c."  (p.  193)  to  adopt  what 
he  supposed  to  have  been  the  opinion  of  the  former, 
that  two  different  colouring  matters  from  India  were 
known  to  the  ancients,  one  naturally  adhering  to  reeds, 
&c.  as  described  by  Pliny,  but  now,  as  he  supposed, 
wholly  unknown  to  the  moderns;  and  the  other,  an  arti- 
jicial  substance  similar  to  our  indigo,  and  which  he 
supposed  to  have  been  extracted  from  the  isatis,  or 
woad,  by  boiling  it  in  dyeing  vessels,  and  collecting 
and  drying  the  scum,  or  skimmings,  (as  Pliny  had 
mentioned  to  be  done  to  obtain  a  pigment  by  the  dyers 
of  Tyrian  purple.)  This,  he  adds,  is  called  in  vulgar 
language,  "  Endego,"*^  and  is  brought  by  merchants 
from  India  to  Alexandria,  in  Egypt,  and  to  Syria,  and 
thence  imported  to  this  city  of  Fenice,  now  become 
(says  he)  the  emporium  of  the  whole  world.^ 

*  "  Consequitur  ergo  ut," — «  duo  atramenti  indici  genere  fue- 
rent  a  Dioscoride  constituia,  (unum)  eoruni  prodidit  naturale  quod 
sponte  ab  arundinibus  in  India  paludibus,  instar  spumae  vi  solis 
exiens  humor  concrescebat  colore  purpureo,  cjuo  tamen  /irorsus  ca- 
remua.  Alterum  vcro  indici  genus  scriptum  nobis  reliquit  esse  arte 
factum;  dum  enim  in  cortinis,  hxc  sunt  vasa  infectorum  in  quibus 


182  Philosophy  of  Permanent  Colours, 

This  work  of  Caneparius,  was  printed  in  1619,  at 
Fentce,  (where  he  lived,  and  where  dyeing  was  then 
more  practised,  and  better  understood,  than  in  any 
other  part  of  Europe;)  and  I  adduce  his  testimony 
chiefly  to  correct  an  error  into  which  M.  BerthoUet  ap- 
pears to  have  fallen,  when  (at  p.  22,  of  the  first  volume 
of  his  Elements,  &c.)  he  asserts,  that  the^r*^  indigo 
made  use  of  in  Europe,  was  imported  from  the  East 
Indies  by  the  Dutch,*  The  fact  is,  that  for  a  considera- 
ble time  before  the  first  voyages  of  the  Dutch,  to  the 
East  Indies,  were  made,  indigo,  in  considerable  quanti- 
ties, had  been  imported  through  Egypt  and  Syria,  to 
Italy,  and  employed  in  dyeing.  That  this  was  one  of  the 
uses  of  that  which  Caneparius  mentioned,  as  being 
imported  through  those  countries  from  India,  is  evi- 
dent from  his  next  page  (194),  where  after  noticing  the 
fact,  of  its  having  been  formerly  employed  as  a  medi- 
cine, he  adds,  that  in  his  own  time,  it  was  used  by  the 
dyers  and  writers;  that  the  former  were  accustomed  to 
dissolve  it  in  vats,  with  a  lye  of  wood  ashes,  and  other 
wares,  according  to  their  own   practices,  concerning 

tingunt  pannos,  ebullit  glastum  isatisve  herba  dicatur,  et  vulgo 
guado,  tunc  efflorescit,  innatatque  spumma  purpurea,  quam  seduli 
artifices  detrahunt,  et  siccant."  This,  he  adds,  is  "  quod  vulgus  ap- 
pellat  endego^  corrupto  vocabulo;  hoc  a  mercatoribus  defertur  ex 
India,  Alexandriam  VEgypti,  et  in  Assyriam,  demum  ex  illis  parti- 
bus  in  banc  Venetiarum  Ciritatem  universi  mundi  Emporium  adve- 
hitur"  That  Caneparius  was  not  accurately  informed  of  the  plant 
which  afforded  indigo,  or  of  the  method  in  which  it  was  obtained, 
will  surprise  no  one  who  is  told  that,  according  to  Mr.  Ray,  bota* 
nists,  even  when  he  wrote  in  1688,  were  not  agreed  on  tliis  subject, 
though  the  plant  was  suspected  to  be  a  leguminous  shrub,  belong- 
ing, or  allied  to  the  genus  Colutea. 

*  "  II  parait  meme  que  le  premier,  (indigo)  qui  ait  6te  employe 
en  Europe,  nous  a  ete  apporte  dcs  Indes  orientales  par  les  Hol- 
landais." 


Philosophy  of  Permanent  Colours.  183 

which,  says  he,  it  is  not  my  office  to  give  instruction.* 
Caneparius  was  a  physician,  and  not  likely  to  have  been 
minutely  informed  in  regard  to  these  practices;  and  yet, 
in  the  same  page,  he  describes  very  accurately,  the 
method  of  preparing,  for  dyers'  use,  the  isatisy  from 
which  he  believed  the  indigo  to  have  been  extracted,! 
and  from  which  indigo  may  indeed  be  obtained. 

I  find  among  my  papers,  a  statement,  which  I  made 
some  years  ago,  on  the  authority  of  Sir  Hans  Sloane, 
(and  taken,  as  I  believe,  from  his  Natural  History  of 
Jamaica,  &c.)  importing,  that  the  annual  consumption 
of  indigo  in  Europe,  about  the  year  1620,  (soon  after  the 
time  when  Caneparius  wrote)  amounted  to  350,000lbs.; 
and  that  this  came  principally  by  the  way  of  Aleppo, 
where  it  was  computed  to  cost  4^.  and  6(/.  the  pound. 
It  is  probable,  therefore,  that  the  Dutch  had  not  then 
begun  to  import  indigo,  by  the  Cape  of  Good  Hope; 
or  at  most,  that  they  imported  but  very  little  of  it. 
That  it  had  previously,  for  a  considerable  number  of 
years,  been  imported  through  or  from  Turkey,  is  evi- 
dent from  several  facts,  and  among  others,  from  Mr. 

Hackluyt's  "  Remembrances  for  Master  S ,"  who, 

in  1582,  was  going  to  Turkey,  and,  among  other  things, 
was  instructed  "  to  know,  if  anile^  that  coloureth  blue, 

*  "  Usus  igitur  indici  est  hodierno  tempore  tincioribus,  et  scrip- 
toribus:  nam  dissolvunt  eum  tinctores  in  Caleariis  cum  lixivio,  et 
aliis  more  suo,  haec  tamen  vos  docere  non  est  meum  institutum." 

t  "  Isatis  est  herba,  quae  ante  florem  colligitur,  et  sub  mola  tun- 
ditur,  et  facto  ex  ipsa  cumulo  macei*atur  soli,  mox  in  ma^os 
globos  redacta,  et  sub  tecto  locata  aspergitur  aqua,  ut  magis, 
potiusque,  maceretur  tunc  edit  magnum  fetorem,  et  nigrescit,  et: 
sic  praeparatio  isatis  sive  glasti  dicatur  idem  est,  perficitur  ad 
tincturas,"  p.  1 94.  The  supposition  of  Caneparius,  that  indigo  was 
obtained  from  the  isatis,  or  \yoad-plant,  seems  to  have  been  preva- 
lent even  in  this  country,  so  late  as  1 640,  when  Parkinson,  who 
was  then  treating  of  indigo,  called  it  "  indico,  or  Indian  nvoade.'* 


184  Philosophy  of  Permanent  Colours* 

be  a  natural  commodity  of  those  parts,  and  if  it  be 
composed  of  an  herb?"  See  Voyages,  ii.  p.  161.  Ed. 
1599. 

BischofF  has,  however,  furnished  decisive  evidence 
to  prove  that  the  use  of  indigo  in  Europe,  as  a  dye,  was 
anterior  to  the  first  voyage  made  by  the  Dutch  to  the 
East  Indies.  He  tells  us,  (Versuche,  Sec.)  that  the  ap- 
pellation or  distinction  of  woad  dyers,  among  the  Ger- 
mans, may  be  found  in  a  charter,  dated  so  early  as  the 
year  1339;  that  with  these,  certain  Flemish  and  Italian 
dyers,  who  had  resorted  to  Germany,  were  afterwards 
incorporated   under  the   name  of  Art,   Woad,  and 
Fine  Dyers:  that  they  excited  the  jealousy  and  enmi- 
ty of  a  more  ancient  corporation,  the  black  dyers;  and 
as  indigo  was  employed  by  the  former,  the  black  dyers, 
influenced  by  this  enmity,  exerted  themselves  with  so 
much  success,  in  decrying  this  dyeing  drug,  that  the 
Elector  of  Saxony,  and  Duke  Ernst  the  Pious,  issued 
severe  prohibitions  against  the  use  of  it;  and  that  even 
in  the  Diet  of  the  Empire,  it  was  described  as  a  perni- 
cious eating  devil,  and  corroding  dye  stuff,  **  Fressende 
Teufels^'*^  &c.;  and  for  these  prohibitions  of  the  Elector 
of  Saxony,  he  refers  to  the  Codex  Augusteus,  part  1, 
p.  236,  under  the  dates  of  1521  and  1547;  and  in  re- 
gard to  the  opprobrious  appellations  applied  to  indigo 
in  the  Diet  of  the  empire,  he  refers  to  a  work  printed 
at  Frankfort,  in  1577;  all  which  dates  are  much  earlier 
than  any  of  the  voyages  of  the  Dutch  to  the  East  Indies. 
In  what  way  indigo  was  first  dissolved,  or  used  for 
dyeing  in  Europe,  I  know  not;  but  in  the  old  collection 
of  recipes^  which  I  have  mentioned  in  the  introductory 
part  of  this  volume,  as  translated  from  the  Dutch,  and 
printed  in  London,  so  early  as  1605,  I  find  one  at  p.  32, 
respecting  the  use  of  indigo,  which  is  there  called  flora, 


Philosophy  of  Permanent  Colours.  185 

or  ^^Jloray^'''*^  and  directed  to  be  fermented  by  the  vat 
process,  with  wood  ashes,  bran,  and  greening  weed, 
(probably  weld),  and  the  appearances  indicating  the  fit- 

*  In  the  act  of  the  23d  year  of  Queen  Elizabeth,  cap.  ix,  indigo 
is  desip^nated  by  the  names  of  "  ancle,  alias  blue  tnde." — How  long 
the  vulgar  Italian  name  of  "  endigo"  mentioned  by  Caneparius, 
had  prevailed  in  that  part  of  Europe  I  am  not  able  to  ascertain; 
but  it  appears  to  have  been  afterwards  adopted  and  spelt  with 
exactly  the  same  letters,  in  the  account  of  Canche's  voyage  to 
Madagascar,  and  by  other  French  writers  of  that  time;  and  our 
name  of  indigo  has  manifestly  been  thence  derived. — The  Spa- 
niards and  Portuguese,  who  had  found  the  way  to  India,  by  two 
opposite  courses,  at  a  much  earlier  period,  and  there  became 
acquainted  with  this  production,  adopted  the  Hindu  name  of  anil, 
and  aneileira;  and  these  are  the  nations  by  whom  indigo  was  first 
manufactured  in  America,  viz.  by  the  Portuguese  in  Brazil,  and  by 
the  Spaniards  in  Mexico,  where  they  each  recognized  the  plant 
growing  spontaneously.  It  seems  extraordinary,  therefore,  that 
professor  Thomas  Martyn  should  have  erred,  as  he  has  done,  in 
his  recent  edition  of  Miller*s  Gardener's  Dictionary,  by  represent- 
ing "  nil  or  anil"  as  "  the  American  name"  of  indigo,  and  con- 
cluding, that  the  Portuguese  had  borrowed  their  name  from  the 
Americans,  not  from  the  people  of  India. — Though  the  French  and 
English  were  later  than  the  Spaniards  and  Portuguese,  in  encou- 
raging the  manufacture  of  indigo  in  America,  they  afterwards 
made  considerable  progress  in  it.  The  former  exported  from  the 
island  of  St.  Domingo  only,  in  1774,  2,350,000lbs.  weight  of  this 
commodity;  and  nearly  about  the  same  time,  in  1773,  in  the  space 
of  twelve  months,  1,107,000  pounds  weight  of  it,  were  exported 
from  South  Carolina.  But  in  both  places,  the  manufacture  of  this 
commodity  has  ceased,  from  new,  though  different  circumstances. 
The  deficiencies,  howeve^,  which  might  have  resulted  from  these 
changes,  have  been  fully  obviated  by  an  increasing  production  of 
indigo  in  the  East  Indies.  The  importation  and  sale  of  this  commo- 
dity, at  the  East  India  house,  in  1792,  amounted  only  to  581,8271bs. 
whilst  the  importation  into  Great  Britain,  from  other  parts  of  the 
world,  amounted  to  l,285,927ibs.;  since  which  time  the  latter 
importation  has  gradually  declined  to  less  than  a  fourth  of  the 
former  amount;  whilst  the  importation  from  the  East  ludies,  and 
sales  at  the  India  house  in  the  year  1806,  amounted  to  4,81  lj700lhs. 
Vol.  I.  2  A 


186  Philosophy  of  Permanent  Colours. 

ness  of  the  fermenting  liquor,  to  be  applied  to  the  stuffs 
to  be  dyed,  are  distinctly  pointed  out;  especially  that  of 
its  becoming  green.  How  early  this  had  been  known, 
or  how  long  this  collection  of  recipes  had  existed  in 
Dutch,  or  any  other  language,  previous  to  the  English 
impression  in  1605,  I  cannot  say;  but  there  is,  I  be- 
lieve, no  reason  to  think  that  the  Dutch  had  even  then 
began  to  import  indigo. 

That  this  artificial  production  was  first  obtained  from 
India,  is  proved  by  the  testimony  of  Pliny,  and  other 
ancient  writers,  confirmed  by  a  variety  of  circumstances; 
and  particularly  by  its  name,  which  is  known,  from  nu- 
merous authorities,  to  have  been  nil  in  the  Hindu  lan- 
guage, from  the  earliest  times,  in  which  there  is  any 
authentic  mention  of  it:  and  this  name  still  continues  to 
be  given  by  the  Hindoos,  to  all  the  plants  whence  indi- 
go is  obtained  by  them;  not  excepting  the  nerium  tine- 
torium,  from  which  Dr.  Roxburgh  believed  that  no 
indigo  had  ever  been  obtained  until  his  discovery  re- 
specting it.  The  late  Sir  William  Jones  has  however 
stated  in  the  fourth  volume  of  Asiatic  Researches,  that 
a  Hindoo  peasant,  who  brought  this  shrub  to  him,  gave 
it  the  name  of  w//,  which  signifies  blue  in  the  language 
of  that  country.  "  A  proof,"  adds  he,  "  that  its  quality 
was  known  to  them,  as  it  probably  was  to  their  ances- 
tors, from  time  immemorial." — When  the  Arabs  and 

and  produced  in  sterling  money  1,685,275/.;  and  the  importation 
and  sale  at  the  India  house,  in  the  following  year,  amounted  to 
5,153,966lbs.  and  produced  the  sum  of  1,563,091/.  sterling. — I 
have  no  accurate  account  of  the  sales  of  East  Indian  indigo  since 
1807.  They  may  probably  have  diminished  a  little  within  the  last 
year  or  two,  because  the  obstructions  to  the  exportation,  resulting 
from  the  peculiar  circumstances  of  the  existing  war,  have  conside- 
rably reduced  the  price  of  this  commodity;  the  importance  of 
which,  as  a  dyeing  drug,  greatly  exceeds  that  of  any  other. 


Philosophy  of  Permanent  Colours.  187 

Egyptians  afterwards  obtained  a  knowledge  of  indigo, 
and  of  its  use,  (as  they  did  of  many  other  things),  from 
India,  they  naturally  adopted  the  name,  with  the  sub- 
stance itself;  the  Arabs  caUing  it  nil  and  nir,  as  Julius 
Scaliger  long  since  mentioned,  (in  his  book,  on  plants,) 
and  the  Egyptians  giving  it  the  name  of  nil,  or  neel.  It 
is  stated  in  the  Memoirs  of  the  Baron  de  Tott,  (p.  278,) 
that  the  seeds  of  the  indigofera  tinctoria,  with  which 
the  Egyptians  dye  their  only  garment  (a  linen  shirt)  are 
imported  annually  from  Syria;  Egypt  being  a  hot-house 
which  exhausts  the  plant,  before  the  seeds  can  ripen. 
The  Egyptians,  therefore,  were  not  likely  to  be  the  first 
discoverers  of  a  manufacture,  depending  on  a  plant, 
which  could  not  yield  prolific  seed  in  their  own  country. 
Concerning  the  history  of  the  isatis,  or  woad,  I  shall 
make  but  a  very  few  observations.  It  was  called  by  the 
former  name  among  the  Greeks,  and  particularly  by 
Dioscorides;  but  ifr  bore  that  of  glastum  among  the 
Gauls  and  Germans,  which,  in  their  language,  signified 
glass:  hence  Caesar,  in  the  5th  chapter  of  his  5th  book, 
de  Bello  Gallico,  says,  *'  omnes  vero  se  Brittani  vitro 
inficiunt,  quod  caeruleum  efficit  colorcm:  atque  hoc 
horribiliore  sunt  in  pugnse  aspectu." — Pliny  distin- 
guishes it  sometimes  by  the  Greek,  and  at  other  times 
by  the  Gallic  names;  and  in  the  first  chapter  of  his  22d 
book,  he  mentions  it  as  resembling  the  plantain,  and  as 
being  called  glastum  by  the  Gauls;  and  though  he  does 
not  repeat  Caesar's  observation,  that  the  Britons  made 
their  skins  blue  with  it,  in  order  to  appear  more  terrible 
in  battle,  he  says,  that  their  wives  and  daughters  paint- 
ed their  bodies  with  it,  when  they  appeared  naked,  at 
the  sacred  festivals,  so  as  to  resemble  Ethiopians.  He 
had  previously  mentioned,  in  the  7th  chapter  of  the 
20th  book,  that  this  plant  was  employed  to  dye  wool. 


188  Philosophy  of  Permanent  Colours, 

But  though  the  Britons  in  Caesar's  time  appear  to 
have  cultivated  enough  of  the  vvoad  to  dye  their  skins, 
the  inhabitants  of  this  island  at  a  later  period,  obtained 
it  from  abroad,  to  dye  their  garments;  and,  indeed,  they 
are  said  to  have  depended  wholly  on  the  French  for  it, 
until  1576.  But  in  1582,  Hackluyt  remarked,  that  "  it 
was  then  brought  to  good  perfection,  (in  this  kingdom) 
to  the  great  loss  of  the  French,  our  old  enemies."  (See 
Voyages,  &c.  vol.  ii.  p.  161.  ed.  1599.)  I  do  not  find 
that  the  woad  plant  has  ever  been  observed  to  give  a 
blue  colour  to  the  milk  of  cows,  like  the  indigo,  which, 
when  eaten  by  them,  not  only  renders  their  urine  blue, 
but,  according  to  Dr.  Garden,  of  South  Carolina,  the 
cream  of  their  milk  also  became  "  of  a  most  beautiful 
blue  colour."  See  Phil.  Trans,  vol.  1.  p.  296. 

Gardenia  Genipa. 
The  Genipa  Americana  of  Linit.  has  recently  been 
united  to  the  genus  named  Gardenia,  by  the  late  John 
Ellis,  Esq.,  in  honour  of  Dr.  Garden,  formerly  of  South 
Carolina  Swartz,  on  whose  authority  this  change  was 
principally  made,  has  strangely  represented  this,  as  being 
only  a  shrub,  though  I  have  frequently  seen  the  tree 
growing  50  or  60  feet  high,  with  a  trunk  five  or  six 
feet  in  circumference.  Its  fruit,  (the  only  part  connect- 
ed with  this  subject,)  is  technically  denominated  a  ber* 
ried  drupe^  nearly  of  the  size  and  shape  of  a  lemon,  a 
little  pointed,  and  umbilicated  at  the  end,  and  covered 
by  a  skin,  which,  whilst  unripe^  is  of  a  light  ash  colour, 
with  a  slight  appearance  of  green:  immediately  under 
the  skin,  is  a  white  solid  fleshy  substance,  moderately 
succulent,  about  one  third  of  an  inch  in  thickness,  sur- 
rounding a  soft  pulpy  matter,  of  an  oval  form,  and 
about  an  inch  in  diameter,  consisting  of  two  cells,  in 


Philosophy  of  Permanent  Colours.  189 

which  many  flattened  roundish  seeds  are  nestled  in 
rows. 

If  this  fruit  or  berry,  whilst  unripe,  be  sliced  or 
broken,  and  exposed  to  atmospheric  air,  its  colourless 
substance,  or  the  clear  juice  expressed  from  it,  almost 
immediately  acquires  a  strong  deep  blue  colour,  and  is 
universally  employed  by  the  savage  tribes  of  Guiana 
and  Brazil,  to  stain  their  skins  with  a  variety  of  spots, 
lines,  and  figures,  for  the  purpose  of  ornament  at  their 
feasts  and  dances,  as  well  as  to  render  themselves  terri- 
ble to  their  enemies  when  going  to  war;  as  the  isatis,  or 
woad,  was  employed  by  the  Britons  in  Caesar's  time. 
But  the  most  shigular  circumstance  attending  this  ap- 
phcation  is,  that  no  repetition  of  washing  with  soap, 
nor  any  other  application,  so  far  as  I  could  learn  at  the 
several  times  of  my  being  in  Guiana,  appeared  to  have 
the  smallest  power  to  remove  the  blue  stains  so  pro- 
duced, until  after  some  days,  (generally  nine  or  ten;) 
when  the  epidermis,  or  scarf  skin,  by  perspiration,  rub- 
bing, Sec.  appears  to  wear  away,  and  make  room  for 
another,  which  is  untinged;  and  it  is  in  this  way  only, 
as  I  believe,  that  the  stains  in  question  spontaneously 
and  gradually  disappear,  after  some  days.* 

Oviedo  seems  first  to  have  mentioned  this  tree  by 
the  name  of  xagua;  but  he  describes  the  colour  pro- 
duced by  its  unripe  fruit,  as  being  blacky  adding  that 
the  stain  given  by  it  to  the  skin,  cannot  be  removed  in 
less  than  ten  or  twelve  da}^s;  and  that  it  never  can  be 
effaced  from  the  finger  nails,  until  by  their  growth  or 

*  Since  my  last  return  from  Guiana,  I  find  it  stated  by  Hart- 
sinck,  ('*  Beschryving  van  Guiana,'*  i.  49,)  that  the  acrid  milky 
juice  of  the  fruit  of  the  carica  fiafiaya^  or  papau  tree,  will  remove 
the  stains  in  question;  which,  if  true,  is  a  curious  fact,  and  I  regret 
not  having  been  informed  of  it,  whilst  I  had  proper  means  to  as- 
certain the  truth  exfieritnentally. 


X90  Philosophy  of  Permanent  Colours, 

elongation  the  stained  parts  can  be  removed.  Francis 
Ximenes  afterwards  mentioned  the  tree  by  the  name 
xahuali^  which  it  bore  in  New  Spain;  he  says,  the  stain 
is  only  to  be  removed  from  the  skin  after  fifteen  days, 
and  never  from  the  nails,  except  by  their  growth  and 
separation,  as  explained  by  Oviedo.  Marcgrave,  (Bra- 
zil, p.  90,)  described  the  tree  under  the  names  of  jani- 
paba,  and  janipapa,  by  which  the  BraziHans  called  it, 
and  from  which  the  more  prevalent  name  of  genipa  was 
derived.  He  says,  "  immaturus  fructus  concisus,  et  cuti 
affricatus,  tingit  colore  ex  nigro  sub  caerulescenti,  qui 
nullo  modo  ablui  potest,  sed  post  octo  aut  nona  dies 
sponte  evanescit." 

Piso  (at  p.  138,)  asserts,  that  the  stain  spontaneously 
disappears,  not  only  from  the  skin,  but  from  paper  in 
about  nine  days,  *'  tinctura  enim  illius  corpori,  vel 
charta  illita  circa  nonam  diem  evanescit."  An  assertion 
which  has  been  often  repeated,  and  generally  believed, 
though  it  never  had  any  better  foundation,  than  a  pre- 
sumption, that  because  it  did  not  remain  on  the  skin,  it 
would  not  remain  upon  paper;  and  hence  it  was  con- 
cluded, that  dangerous  frauds  might  be  practised,  by 
writing  with  this  colour  instead  of  ink.  Coppier  had, 
indeed,  made  this  assertion  some  years  before,  ("  His- 
toire  et  Voyages  des  Indes  occidentales,"  printed  at 
Lyons,  1645,  p.  91.)  And  he  pretended  that  the  fact 
had  been  first  discovered  by  himself,  and  that  he  had 
endeavoured  to  consign  it  to  oblivion  for  the  prevention 
of  fraud.  There  was,  however,  no  foundation  for  this 
pretension.  I  have  now  before  me,  both  parchment  and 
paper,  on  which  I  wrote  with  the  juice  of  the  unripe 
fruit  of  the  tree  under  consideration,  seven  years  ago, 
and  it  has  not,  as  far  as  I  can  discover,  suffered  the 
smallest  decay;  and  there  is  good  reason  to  believe  it 
would  prove  even  more  durable  than  the  common  writ- 


Philosophy  of  Permanent  Colours,  191 

ing  ink,  though  it  differs  from  it,  by  inclining  much 
more  to  the  dark  blue  colour.  The  fable^  however,  of 
the  fugitive  nature  of  this  ink,  and  the  dangerous  pur- 
poses to  which  it  might  be  applied,  was  so  generally 
and  firmly  believed,  by  the  inhabitants  of  Essequebo 
and  Demerary,  that  1  was  induced  to  report  it  as  credi- 
ble in  the  volume,  which,  at  an  early  age,  I  published  re- 
specting the  Natural  History  of  Guiana,  in  1769.* 

This  tree,  like  the  nerium  tinctorium,  asclepias  tingens, 
&c.  belongs  to  the  natural  order  of  Contorts,  and  is  known 
at  Essequebo,  Demerary,  and  Berbice,  by  the  Arroxvauk 
name  oUauna^  and  at  Surinam  by  that  oUapouripa,  which 
undoubtedly  was  borrowed  from  some  of  the  neighbour- 
ing tribes,  probably  the  Carribees,  with  whom  the  first 
(English)  settlers  in  that  colony  had  more  communication 
than  with  any  other;  though  I  cannot  find  this  name  in  any 
vocabulary  of  the  language  of  that  people.  Mad.  Merian 
has  mentioned  this  tree  inaccurately,  under  the  name  o^ta- 
hrouba^  and  has  intended  to  represent  a  branch  of  it,  at  her 

*  Francis  Ximenes  mentions  that  tricks  were  sometimes  prac- 
tised with  the  juice  of  this  fruit,  by  privately  mixing  it  M'ith  rose 
water,  and  giving  it  to  the  ladies  in  New  Spain;  and  Dutertre,  in 
his  Account  of  the  French  West  India  Islands,  writing  of  this  tree 
says,  "  il  porte  le  fard  des  chambrieres  nouvellement  venues."  He 
adds  that  the  simple  maid  servants,  who,  in  considerable  numbers, 
about  tUat  time,  came  to  the  West  Indies  from  France,  were  told 
upon  their  arrival,  that  unless  they  washed  their  hands  and  faces 
with  the  (colourless)  juice  of  this  fruit,  their  skins  would  become 
blacky  and  that,  believing  this,  they  eagerly  collected  and  applied 
the  supposed  means  of  preserving  their  complexions,  and  were 
astonished,  soon  after  the  application,  to  find  their  faces  and  hands 
covered  with  a  hideous  dark  blue  stain,  which  nothing  could  re- 
move for  nine  or  ten  days.  He  indeed  mentions  his  having  mar- 
ried considerable  numbers  of  them,  before  this  stain  had  been 
removed,  and  repeats  the  fable  respecting  the  supposed  frauds 
which  might  be  practised  by  using  the  juice  of  this  fruit  as  a 
substitute  for  ink. 


192  Philosophy  of  Permanent  Colours. 

43d  plate,  but  has  transposed  xht  explanation,  or  descrip- 
tion,  belonging  to  this  plate,  by  joining  it  to  her  48th  plate, 
and  connecting  to  the  former  that  which  relates  to  the 
latter;  a  blunder  which  no  person  seems  to  have  before 
noticed. 

When  this  volume  was  first  published  in  1794, 1  believ- 
ed, and  stated  my  belief,  that  the  blue  colour  of  the  fruit  in 
question,  like  that  of  indigo,  resulted  from  a  combination 
of  oxygene,  with  a  vegetable  basis;  and  in  fact  that  it  was 
similar  to  indigo.  And  this  belief  was  principally  founded 
upon  my  having,  when  ^t  Surinam,  in  1770,  applied  the 
colourless  juice  of  the  fruit  to  pieces  of  linen  and  calico, 
and  seen  the  parts  to  which  it  was  applied  speedily  be- 
come blue,  as  happens  with  the  indigo  and  woad  plants; 
and  upon  my  having  found  that  the  colour  so  produced 
was  not  discharged  by  repeated  washings  with  soap,  nor 
considerably  injured  by  exposure  to  the  sun  and  air  for 
several  days:  my  experiments  at  that  time  were,  however, 
but  few  in  number,  and  made  under  the  disadvantage  of 
being  then  but  little  acquainted  with  the  subject  of  dyeing: 
wishing,  therefore,  for  greater  certainty  respecting  the  na- 
ture and  properties  of  this  colouring  matter,  I  determined, 
when  I  visited  Guiana  a  third  time,  in  1805,  if  possible, 
fully  to  investigate  the  subject.  And  accordingly  having 
observed,  soon  after  my  arrival  in  Demerary,  a  young 
gardenia  genipa  tree  growing  on  the  plantation  Rein- 
steen,  then  belonging  to  Messrs.  Brummell  and  Addi- 
son, which  tree,  though  probably  bearing  for  the  first 
time,  exhibited  two  or  three  dozens  of  the  berries  or 
fruit,  each  about  the  size  of  a  nutmeg.  I  informed  Mr. 
Brummell  of  my  wish  to  make  experiments  with  them 
at  the  proper  time,  and  with  his  usual  kindness,  he  im- 
mediately ordered  that  they  should  be  all  carefully  pre- 
served for  my  use.  In  a  few  weeks  after,  I  observed  the 
tree  to  have  shed  all  its  leaves,  (as  happens  to  trees  of 


Philosophy  of  Permanent  Colours.  193 

this  species  at  certain  seasons,)  and  that  it  afForded  the 
uncommon  spectacle  of  a  leafless  tree  bearing  fruit. 

About  this  time,  circumstances  connected  with  the 
state  of  my  health,  determined  me  to  return  immediately 
to  Europe,  by  the  way  of  Barbadoes;  and  having  no  lei- 
sure to  make  even  a  single  experiment,  the  fruit  of  this 
tree,  which  had  then  almost  attained  its  full  growth, 
were  all  gathered,  and  embarked  with  my  baggage. 
But  finding  soon  after  my  arrival  at  Barbadoes,  that  they 
were  becoming  soft,  and  in  danger  of  spoiling,  before  I 
could  conveniently  make  the  experiments  which  I  in- 
tended, I  caused  them  to  be  sliced  and  dried  in  the  sun; 
presuming  that  they  might  afterwards  be  preserved  seve- 
ral years,  like  the  indigo  plant,  in  a  state  fit  for  my  ex- 
periments. But  while  this  was  doing,  the  sudden  transition 
of  the  whole  inner  colourless  substance  of  the  sliced  fruit, 
to  a  full  dark  blue,  without  any  intermediate  yellow  or 
green  tint,  engaged  my  attention,  as  indicating  an  im- 
portant difference  between  this,  and  the  basis  of  indigo; 
for  it  was  hardly  credible  that  the  affinity  for  oxygene 
should  be  so  much  greater  in  the  former  than  in  the  lat- 
ter, as  to  enable  it  at  once  to  become  blue,  without  even 
the  momentary  appearance  of  an  intervening  green. 

By  the  part  which  I  took  in  slicing  this  fruit,  my  fin- 
gers were  deeply  stained;  and  as  this  stain  might  well 
seem  indecorous  to  the  gentlemen  and  ladies,  with  whose 
hospitalities  I  was  daily  honoured,  I  spared  no  pains  to 
remove  it,  by  repeated  washings  with  soap,  alkalies,  &c. 
and  by  frequent  applications  of  lemon,  and  lime  juice, 
but  without  producing  any  sensible  diminution  of  this 
troublesome  dark  blue  colour,  until  it  disappeared  in  the 
usual  way,  by  an  apparent  abrasion  of  the  cuticle. 

I  did  not  neglect,  when  in  Barbadoes,  to  apply  some 
of  the  juice  of  the  sliced  fruit,  by  which  my  fingers  were 
stained,  to  pieces  of  calico,  impregnated  with  alumine. 

Vol.  I.  2  B 


194  Philosophy  of  Permanent  Colours. 

and  the  oxide  of  iron,  as  well  as  to  some  which  had  no 
impregnation,  and  I  afterwards  found  that  neither  of 
these  bases  had  any  affinity  for  the  colouring  matter  un- 
der consideration,  it  being  in  no  respect  changed  thereby. 
The  calico  without  any  basis,  had  acquired  a  very  dark 
blue  tinge,  which  was  not  altered  by  washing  with  soap, 
nor  by  exposure  to  sun  and  air  for  some  days;  though  in 
this  respect  it  seemed  to  be  less  permanent,  than  I  had  be- 
lieved it  to  be,  from  my  former  experiments  in  Surinam, 

Since  my  return  to  London,  I  have  made  such  trials 
as  to  me  appeared  suitable,  with  the  sliced  and  dried 
fruit  of  the  gardenia  genipa,  which,  though  more  than 
seven  years  have  elapsed,  still  retains  a  dark  blue  colour; 
but  this  manifestly  depends  on  principles  very  different 
from  those  of  indigo.  For  it  is  soluble  both  in  potash 
and  soda  alone;  and  when  lime  and  orpiment  were  added 
to  these,  no  change  of  colour  ensued  (from  blue  to  green,) 
indicating  a  susceptibility  of  deoxidation.  Sulphuric  acid 
seemed  to  brighten  the  blue  colour  as  it  does  that  of 
indigo.  But  (unlike  sulphate  of  indigo,)  this  mixture 
appeared  to  have  no  affinity  for  vegetable  substances, 
and  so  little  for  the  animal,  that  cloth  by  long  boiling  in 
the  blue  liquor,  would  only  receive  a  slight  drab  colour. 
Nor  does  the  juice  of  the  fruit  seem  capable  of  perma- 
nently staining  the  fingers,  after  it  has  already  become 
blue.  The  addition,  whatever  it  be,  which  occasions  the 
blue,  if  made  before  it  touches  the  skin,  rendering  it  in- 
capable afterwards  of  attaching  itself  either  to  animal  or 
vegetable  substances.  Nitric  acid  changes  the  blue  to 
yellow,  as  it  does  that  of  indigo. 

Several  writers  have  asserted,  that  the  fruit  of  the  gar- 
denia genipa  when  ripe^  becomes  yellow,  and  loses  its 
disposition  to  assume  a  blue  colour.  Whether  this  co- 
lourable property  was  in  any  degree  affected,  by  my 
having  kept  the  fruit  in  question,  until  it  was  approach- 


Philosophy  of  Permanent  Colours.  195 

ing  towards  rottenness,  (which  might  produce  effects 
like  those  of  ripeness),  I  know  not;  but  as  its  blue  colour 
evidently  results  from  causes,  differing  greatly  from  those 
which  produce  the  colour  of  indigo,  it  seems  very  desi- 
rable to  ascertain  their  nature;  though  I  think  this  can 
only  be  done  by  trials  upon  the  unripe  and  recently 
gathered  berries,  which,  while  their  juice  remains  co- 
lourless, might  be  placed,  some  in  vacuo^  others  in  the 
several  gases  separately,  and  exposed  to  the  sun's  rays, 
as  well  as  kept  in  obscurity^  to  discover  which  of  these 
situations  and  agents  contributed  most,  either  to  hasten 
or  retard  the  production  of  the  blue  under  consideration. 

Brown,  in  his  History  of  Jamaica,  p.  143,  observes, 
that  "  the  pulp  of  the  berries  of  the  Randia  aculeata, 
Linn,  (called  in  that  island  the  indigo  berry,  and  which 
grows  plentifully  on  the  smaller  branches  of  the  plant,) 
is  very  thick,  and  stains  paper  or  linen  of  a  fine  fixed 
blue  colour.  I  have  tried  it  (continues  he)  on  many  oc- 
casions, and  have  always  observed  it  to  stand,  though 
washed  with  either  soap  or  acids;  but  it  does  not  com- 
municate so  fine  a  colour  with  heat.  It  would  prove  (he 
adds)  an  excellent  fixed  blue  in  all  manner  of  paints  and 
prints,  if  it  could  be  obtained  in  any  quantity;  but  the 
berry  is  not  very  succulent,  and  the  people  as  yet  are  not 
very  industrious  in  these  parts." 

This  plant,  like  the  genipa,  has  recently  been  added  to 
the  genus  gardenia^  (under  the  name  of  gardenia  acu- 
leata,) and  it  is  remarkable  that  their  generic  characters 
being  similar,  their  fruit  also  should  yield  blue  colouring 
matters,  which,  as  far  as  I  know,  seem  to  resemble  each 
other.  The  indigo  berry,  in  like  manner,  belongs  to  the 
natural  order  of  contort  a  ^  which,  more  than  any  other, 
contains  plants  yielding  the  blue  colour. 

Mr.  Martin  Lister  (in  the  Vlth  Vol.  of  the  Philoso- 
phical Transactions,  page  2132,)  mentions  that  "  the 


196  Philosophy  of  Permanent  Colours. 

seed  husks  of  glastum  sylvestre,  old  gathered  and  dry, 
being  diluted  with  water,  stain  a  blue,  which,  upon  the 
aiFusion  of  lye,  strikes  a  green;  which  green  or  blue, 
being  touched  with  the  oil  of  vitriol,  dyes  a  purple;  and 
all  these  colours  (says  he)  stand."  Some  of  the  mush- 
rooms also  become  blue,  when  exposed  to  atmospheric 
air.  The  same  effect,  according  to  Sennebier,  happens 
to  the  milky  juice  of  the  tithymalus  euphorbia,  Linn. 

It  is  mentioned  somewhere  in  the  Swedish  Memoirs^ 
by  Cronsted,  that  the  stalks  of  the  polygonum  fagopy- 
rum,  Linn,  by  fermentation  in  water,  afford  a  blue  which 
did  not  change  either  by  acids  or  alkalies. 

Green  Indigo. 

About  the  year  179Q,  Mr.  Alderman  Prinsep,  who 
had  then  lately  returned  from  India^  gave  me  a  specimen 
of  indigo  obtained  there^  as  he  informed  me,  from  a  tree, 
(which  I  then  suspected  to  be  the  panitsjica-maram,  of 
the  hortus  malabaricus,  though  I  now  suppose  it  must 
have  been  produced  from  the  nerium  tinctorium,  lately 
mentioned;)  and  he,  at  the  same  time,  gave  me  a  very 
small  piece  of  a  hard  green  substance,  likewise  produced 
in  the  East  Indies,  and  which  he  called  green  indigo. 

Upon  seeing  it,  I  flattered  myself  with  a  hope  of  its 
proving  to  be  what  the  late  Mons.  de  Poivre  had  men- 
tioned in  a  little  work,  published  under  the  title  of 
**  Voyages  d'un  Philosophe,"  &c.  as  obtained  by  the 
inhabitants  of  Cochinchina  from  a  plant  called  tsaiy 
which,  when  macerated  and  fermented  like  indigo,  yields 
a  green  fecula,  capable  of  dyeing  a  fine,  as  well  as  a  last- 
ing emerald,  or  green  colour.*   The  quantity  of  this 

*Loureiro  mentions,  (torn.  i.  p.  25,  of  the  original  Lisbon  edi- 
tion,)  the  justicia  tinctoria,  as  growing  wild  in  Cochinchina,  add- 
ing, «  folia  viridi  colore  staturata,  eodem  telas  pulchre  imbuunt." 
Whether  the  plant,  whose  leaves  alone  are  here  represented  as 


Philosophy  of  Permanent  Colours,  197 

^een  substance  so  put  into  my  hands,  was  much  too 
small  even  for  a  single  decisive  experiment.  I  however 
divided  it  into  three  parts.  One  of  these  I  put  into  boil- 
ing water,  which  appeared  to  have  no  action  upon  it; 
but  it  was  afterwards  dissolved  by  a  little  oil  of  vitriol, 
like  common  indigo,  producing,  however,  a  green,  in- 
stead of  a  blue  colour.  A  second  of  these  parts  I  dissolv- 
ed with  a  little  caustic  alkali  and  orpiment,  in  order  to 
see  whether,  excepting  the  difference  of  colour,  it  would 
possess  properties  similar  to  those  of  indigo,  when  dis- 
solved by  the  same  means,  and  like  the  latter  be  able  to 
produce  a  fixed  colour  on  linen  or  cotton  by  topical  ap- 
plication. This,  however,  it  did  not  seem  to  be  capable 
of  doing:  the  remaining  part  I  put  into  a  little  spirit  of 
wine,  which  dissolved  a  portion  of  it,  though  very  slowly; 
a  circumstance  in  which  it  differs  materially  from  indigo, 
and  seems  in  some  degree  to  resemble  that  green-colour- 
ed fecula  which  some  plants  afford,  and  particularly  the 
cruciform,  when  fermented  like  the  indigo  plant  in  warm 
weather,  I  confess,  however,  that  these  experiments  were 
made  on  such  very  small  quantities  of  the  substance  un- 
der consideration,  that  very  little  dependence  ought  to 
be  placed  upon  them.  But  this  is  certain,  that  if  a  sim- 
ple or  homogeneous  green  colouring  matter  exists,  and 
can  be  discovered,  with  properties  in  other  respects  simi- 
lar to  those  of  indigo,  it  will  be  a  most  important  addi- 
tion to  the  Materia  Tinctoria. 

Barasat  Verte, 

In  the  year  1793,  Messrs.  John  and  Francis  Baring, 

and  Co.,  received  from  R.  C.  Birch,  Esq.  of  Calcutta, 

parcels  of  two  new  drugs,  intended  for  dyeing;  samples 

of  which  were  put  into  my  hands,  with  a  request  that  I 

capable  of  producing  a  green  dt/e,  has  any  relation  to  the  fsai  of 
M.  de  Poivre,  I  know  not. 


198  Philosophy  of  Permanent  Colours. 

would  make  suitable  trials  of  their  merits;  and  with  a 
paper  containing  some  explanations  which  had  accompa- 
nied them  from  India.  One  of  these  (and  the  only  one 
which  I  shall  notice  at  this  time)  was  called  Barasat 
Verte,  and  was  formed  into  dry  hard  cakes,  resembling 
in  size  and  shape  those  of  the  indigo  sent  from  Bengal; 
but  of  a  dark  dull  green  colour.  It  was  stated  to  be  a 
simple  substance,  and  to  have  been  prepared  with  water 
and  fire  only,  *'  from  an  indigoferous  plant,  an  ever- green, 
with  leaves  somewhat  resembling  those  of  the  laurel, 
bearing  large  clusters  of  small  yellow  flowers,  and  pro- 
ducing seed  in  large  pods,  pointed  at  the  end,  and  it  was 
added,  that  the  seed  did  "  not  vegetate  in  BengaW'^  It  was 
also  represented  as  giving  a  durable  light  green  colour, 
without  any  mordant  or  basis,  to  silk  and  wool;  and  to 
be  incapable  of  dyeing  dark  green  without  the  aid  or  ad- 
dition of  some  blue  colouring  matter.  To  bring  this 
green  indigo  into  a  state  fit  for  use,  it  was  directed  to  be 
finely  levigated  with  sand,  and  then  boiling  hot  water  was 
to  be  poured  upon  the  powder  in  a  suitable  vessel;  and 
being  left  to  settle,  the  water  '^  tinged  with  a  dirty  brown 
colour  was  to  be  poured  off;"  and  these  washings  were 
to  be  repeated  until  the  water  came  from  the  powder  co- 
lourless; and  then  to  the  remaining  powder  an  equal 
quantity  of  fixed  vegetable  alkali,  obtained  by  calcining 
salt-petre  upon  burning  charcoal,  was  directed  to  be 
added,  with  a  proportionate  quantity  of  water,  and  the 
mixture  made  to  boil  for  two  or  three  hours;  after  which, 
if  was  to  be  left  "  to  digest  for  two  days  at  least."  In  this 
preparation,  diluted  with  boiling  water,  the  silk  or  wool- 
len stuff  was  directed  to  be  dipped  for  the  space  of  half 
an  hour,  and  then  washed  with  soap  in  water;  a  longer 
dipping  was  represented  as  giving  no  greater  body  or 
depth  of  colour. 


Philosophy  of  Permanent  Colours,  199 

After  what  has  been  just  mentioned  on  the  subject  of 
green  indigo,  it  will  naturally  be  concluded,  that  my 
curiosity  must  have  been  greatly  excited  by  that  now 
under  consideration;  and  indeed  I  lost  not  a  single  mi- 
nute in  making  such  a  trial  of  it,  as  would  decisively 
ascertain  whether  it  really  possessed  the  properties  of 
indigo,  with  only  the  difference  of  a  green  instead  of  a 
blue  colour.  This  was  by  powdering  and  boiling  it  in 
water  with  a  suitable  portion  of  lime,  potash,  and  red 
orpiment,  as  is  practised  in  making  the  printer's  blue  for 
penciling,  (see  page  154,  &c.);  and  in  doing  this,  I  soon 
perceived,  with  great  satisfaction,  that  the  mixture  ex- 
hibited exactly  the  same  smell,  and  the  same  appearances, 
as  those  which  arise  in  making  the  printer's  blue;  the 
surface  of  the  liquor  was  covered  with  a  fine  shining 
copper-coloured  scum,  and  beneath  this,  when  separated, 
the  liquor  itself  exhibited  a  lively  green.  Being  impatient 
to  see  how  far  its  effects  were  similar  to  those  of  indigo 
dissolved  in  this  way,  1  applied  some  of  the  green  liquor 
as  expeditiously  as  possible,  by  the  pencil,  to  a  bit  of 
calico,  and  soon  perceived  that  it  consisted  of  t^vo  very 
dissimilar  colouring  matters;  one,  which  proved  to  be 
true  indigo,  was  immediately  revived  by  an  absorption 
of  oxygene,  (as  happens  to  the  printer's  blue  when  so 
applied,)  whilst  another  part  of  the  liquor  spread  itself 
farther,  and  retained  a  kind  of  olive  green  colour,  which 
the  air  did  not  change. 

The  calico,  after  being  dried,  was  washed  with  soap, 
and  that  part  of  the  liquor  which  had  spread  farthest,  and 
retained  the  olive  green  colour,  was  soon  wholly  washed 
out,  leaving  behind  the  pure  indigo,  adhering  to  the  spots 
and  strokes  where  it  had  been  applied.  Having  thus  con- 
vinced myself  that  this  substance  contained  a  portion  of 
true  indigo,  I  powdered  an  ounce  of  it,  and  mixed  the 
powder  with  six  times  its  weight  of  sulphuric  acid,  as  in 


200  Philosophy  of  Permanent  Colours. 

making  the  sulphate  of  indigo  for  Saxon  blue:  in  about 
twenty-four  hours  the  powder  appeared  to  be  nearly  all 
dissolved,  and  the  solution  was  of  a  blue  colour,  with  a 
greenish  tinge:  and  by  putting  a  little  of  it  into  warm 
water,  and  dyeing  a  small  piece  of  flannel  therein,  a  full 
Saxon  blue  was  soon  produced;  though  the  colour  had  a 
greenish  cast,  occasioned  manifestly  by  the  same  olive- 
coloured  matter  which  I  have  just  mentioned  as  having 
showed  itself  upon  the  calico.* 

I  afterwards  tried  the  method  recommended  by  the  au- 
thor of  this  discovery,  of  separating  the  yellowish  brown 
colouring  matter  from  the  powdered  green  indigo,  by 
repeated  ablutions  with  hot  water,  and  then  employing  a 
pure  caustic  vegetable  alkali  to  dissolve  the  residuum.  In 
this  way  I  obtained  a  solution  which,  upon  wool,  dyed  a 
light  olive  or  apple  green;  I  found,  however,  as  I  had 
foreseen,  that  none  of  the  true  indigo  had  been  dissolved, 
either  by  these  last  trials,  or  those  made  in  Bengal,  it 
being  impossible,  as  I  have  formerly  explained,  to  dis- 
solve indigo  by  caustic  alkali  alone;  and  indeed  the  dis- 
coverer of  this  preparation,  in  the  account  which  he 
transmitted  from  Bengal,  candidly  acknowledges  that  he 
had  never  been  able  to  dissolve  the  supposed  green  in- 
digo "  eniirely,  a  considerable  quantity  having  always 
remained  precipitated  at  the  bottom  of  the  vessel."  And 
this  insoluble  residuum,  (which  appears  to  have  been 
lost,  or  at  best  to  have  remained  wholly  useless  in  all  the 
experiments  made  in  Bengal),  I  found  by  further  trials  to 
be  true  indigo.  For  by  separating  the  solution  made  by 

*  A  small  bit  of  the  Barasat  Verte  being  ignited,  it  burnt  with  a 
brisk  red  flame,  emitting  fumes,  of  which  a  considerable  part  ex- 
hibited the  fine  purple  tint  peculiar  to  those  of  indigo.  It  left  a 
residuum,  equal  to  about  half  its  bulk,  of  a  dark  chocolate  colour, 
of  which  carbon  seemed  to  constitute  a  considerable  part,  but  this 
I  did  not  particularly  examine. 


Philosophy  of  Permanent  Coloun.  201 

caustic  vegetable  alkali  from  the  residuum,  then  pouring 
upon  the  latter  farther  portions  of  caustic  alkali  in  hot 
water,  until  the  lixivium  came  away  colourless;  and  after- 
wards submitting  what  remained  to  the  action  of  muriatic 
acid,  to  dissolve  any  heterogeneous  matters  which  the 
alkaline  menstruum  had  left  behind,  I  at  length  obtained 
a  considerable  quantity  of  indigo,  of  a  middling  quality; 
part  of  which,  being  dissolved  by  sulphuric  acid,  dyed 
wool  of  a  good  Saxon  blue  colour,  without  any  of  the 
greenish  tinge  which  had  attended  my  first  trials;  and 
another  part  being  dissolved  by  potash,  lime,  and  red  orpi- 
ment,  as  for  the  printer's  topical  blue,  produced  the  usual 
effects  of  indigo  in  this  way.  Having  applied  the  acetite 
of  alumine  topically  to  a  piece  of  cotton,  as  is  practised 
in  calico  printing,  and  dyed  one  part  of  it  in  the  yellowish 
brown  coloured  liquor,  which  had  been  obtained  by  pour- 
ing hot  water  on  the  supposed  green  indigo  in  powder, 
and  another  part  in  the  olive  green  liquor,  obtained  from 
the  same  powder  by  caustic  vegetable  alkali,  I  found 
that,  though  each  imbibed  a  different  colour,  neither  was 
fixed  upon  the  figures  which  had  been  printed  with  the 
aluminous  basis,  or  on  the  parts  to  which  no  mordant  or 
basis  had  been  applied,  and  that  the  colours  were  re- 
moved by  washing  widi  equal  facility  from  every  part:  a 
certain  proof  that  the  yellowish  brown  and  olive  green 
colouring  matters  were  not  of  the  adjective  kind,  (having 
no  affinity  with  the  aluminous  basis,)  and  that  they  are 
not  likely  to  be  of  any  use  in  dyeing;  for  though  they 
should  prove  lasting  upon  woollens,  there  are  many 
other  and  much  cheaper  means  already  in  use  for  giving 
colours  of  this  kind  to  wool.  It  seems  evident,  therefore, 
that  the  true  nature  of  the  supposed  green  indigo  was 
but  very  little  known  to  the  discoverer  thereof;  and  that 
its  useless  heterogeneous  parts  were  the  only  ones  which 
Vol.  I.  2  C 


202  Philosophy  of  Permanent  Colours. 

produced  the  colours  dyed  in  Bengal,  and  which  induced 
him  to  send  it  to  Europe  as  a  dyeing  drug. 

Whether  the  supposed  green  indigo  owes  its  produc- 
tion to  an  insufficient  combination  of  oxygene;  or,  in 
other  words,  whether  the  matters  which  dyed  the  yel- 
lowish brown,  and  the  olive  green  colours,  before  men- 
tioned, are  similar  to  that  which  forms  the  basis  of  true 
indigo,  and  capable  of  being  converted  thereto  by  a  longer 
fermentation,  agitation,  &c.;  or  whether  they  are  of  a  na- 
ture essentially  different  from  the  basis  of  indigo,  though 
naturally  combined  with  it  in  the  particular  plant  whence 
the  substance  under  consideration  is  extracted,  are  im- 
portant questions  which  I  am  unable  to  answer.  I  have 
indeed  mixed  the  supposed  green  indigo,  in  powder, 
with  water,  and  kept  the  mixture  for  several  days  at  a 
degree  of  warmth  suited  to  promote  a  fermentation,  but 
without  being  able  in  this  way  to  render  its  colour  blue, 
or  increase  the  proportion  of  true  indigo  which  it  had 
before  contained:  but  perhaps  I  might  have  been  more 
successful  with  a  greater  quantity,  or  a  larger  fermenta- 
ble mass,  than  what  I  was  able  to  employ  in  this  way. 

I  have  had  reason  to  conclude,  that  the  supposed  green 
indigo,  either  from  a  redundance  of  colouring  matter  in 
the  plant  from  which  it  was  extracted,  or  from  some 
other  cause,  may  be  obtained  at  much  less  expense  than 
the  true  indigo;  and  if  this  be  the  case,  it  must  doubdess 
"prove  a  very  important  discovery,  if  the  yellowish  brown 
and  olive  green  matters  are  capable  of  being  changed  to 
indigo,  by  a  farther  combination  of  oxygene:  and  even 
if  this  should  not  be  the  case,  perhaps  the  plant  may  de- 
serve attention,  on  account  of  the  portion  of  true  indigo 
which  it  unquestionably  aftbrds;  and  which,  by  an  altera- 
tion in  the  process,  might  doubtless  be  precipitated  and 
collected,  free  from  the  other  matters  before  mentioned, 
which,  at  best,  can  only  be  considered  as  a  troublesome 


Philosophy  of  Permanent  Colours.  203 

incumbrance,  without  any  such  benefit  as  Mr.  Birch  ap- 
pears to  have  expected  fi'om  them. 

The  preceding  account  of  the  Barasat  Verte^  was 
pubhshed  by  me  in  1794,  excepting  the  names ^  which  I 
did  not  consider  myself  as  at  liberty  to  mention.  I  had 
not  then  been  informed  that  when  my  attention  to  this 
subject  was  requested  by  Messrs.  Baring,  the  nearest 
relation  of  Mr.  Birch  in  this  country,  had  also  engaged 
Dr.  Higgins  to  employ  his  chemical  science  and  means 
upon  the  same  matter;  and,  consequently,  the  report 
which  I  made,  and  which  was  transmitted  by  Messrs. 
Baring  to  Calcutta,  was  founded  solely  upon  the  results 
of  my  experiments.  I  discovered  afterwards,  however, 
by  some  letters  from  Mr.  Birch,  (of  which  extracts  were 
communicated  to  me,)  that  the  report  of  Dr.  Higgins,  in 
regard  to  the  merits  and  value  of  the  Barasat  Vcrte,  had 
been  much  more  favourable  than  mine;  he  having,  ac- 
cording to  Mr.  Birch's  summary  account,  stated  it  to  be 
"  a  novelty,  producing  fine  dyes,  going  farther  than  in- 
digo, and  rivalling  it,  in  the  solidity  and  lustre  of  its 
colours."  Fortunately  for  Mr.  Birch,  he  did  not,  on  the 
strength  of  this  report,  precipitately  engage  in  an  exten- 
sive manufacture  of  this  article,  as  he  might  have  done, 
if  my  opinion  had  been  equally  favourable.  One  of  his 
letters  contains  this  observation:  "  Dr.  Bancroft's  expe- 
riments, and  remarks,  appear  to  have  been  made  with 
much  good  sense,  candour,  and  kindness;  had  he  given 
as  favourable  an  opinion  as  Dr.  Higgins,  I  should  have 
had  more  dependence  than  I  can  now  have,  &c." 

Mr.  Birch  did  not,  however,  relinquish  this  object,  un- 
til by  sending  to  this  country  several  parcels  of  the  Ba- 
rasat Verte,  and  getting  it  used  by  dyers,  he  became 
fully  satisfied,  that  it  had  no  other  value  than  that  of  the 
indigo  contained  in  it;  and  that,  as  indigo,  this  was  not 
the  most  advantageous  form,  or  method  of  preparing  it. 


204  Philosophy  of  Permanent  Colours, 

The  manufacture  of  this  dye  being  now  abandoned,  I 
may,  without  impropriety,  intimate  my  belief,  that  the 
Barasat  Verte  was  obtained  from  the  taroom  akkar  of 
Mr.  Marsden,  (lately  mentioned  at  p.  140,)  which  Dr. 
Roxburgh  has  denominated  asclepias  tinctoria,  (belong- 
ing to  the  natural  order  of  contortae,)  and  which  was 
introduced  at  Calcutta,  a  little  before  Mr.  Birch  pro- 
duced the  Barasat  Verte.  What  the  latter  mentions  of 
its  leaves,  p.  198,  agrees  with  Mr.  Marsden's  account 
of  them;  and  Mr.  Birch's  observation,  that  the  seed  did 
not  vegetate  in  Bengal,  is  conformable  to  Dr.  Rox- 
burgh's remark,  that  it  did  "  not  ripen  its  seed^^  in  the 
botanic  garden  at  Calcutta,  nor  in  that  of  Samulcota. 
(See  Trans,  of  the  Society  of  Arts,  &c.  vol.  28,  p.  302.) 
The  latter  also  mentions  hot  water,  as  necessary  to  ex- 
tract the  colouring  matter  of  the  leaves  of  the  taroom 
akkar,  which  enables  us  to  understand  why  Mr.  Birch 
has  included  fire  among  the  means  employed  to  prepare 
the  Barasat  Verte.  Probably  this  *'  stately  useful  creeper," 
as  Dr.  Roxburgh  terms  it,  contains  a  larger  proportion 
of  extractive  matters,  than  other  plants  yielding  indigo, 
(which  the  hot  water  would  copiously  extract,)  and  the 
precipitants  employed  by  Mr.  Birch,  may  have  been 
such  as  to  throw  these  matters  down  abundantly,  inter- 
mixed with  the  indigo. 

Dr.  Roxburgh  describes  another  species  of  swallow 
wort,  under  the  name  of  asclepias  tingens;  which  is,  he 
says,  "  a  large  twining  shrubby  plant,  brought  from 
Pegu  in  1795,  to  the  botanic  garden  at  Calcutta,  where 
it  thrives  well."  He  adds,  "Dr.  Buchanan,  who  brought 
the  plant,  informed  me,  that  from  its  leaves  the  Burmah 
people  prepare  a  green  dye."—"  I  have  made,  (he  adds) 
a  variety  of  experiments  with  the  view  of  obtaining  the 
green  dye  above  mentioned,  but  without  success." — ^ 
"But  this  information  is  from  so  respectable  a  source, 


Fhilosophy  of  Permanent  Colours,  205 

as  to  induce  me  to  hope,  some  better  qualified  person 
may  be  able  to  discover  how  this  green  dye  is  to  be  ob- 
tained and  applied."  See  Trans,  of  the  Society  of  Arts, 
&c.  vol.  28,  p.  305. 

Formerly  the  soot  of  burnt  wood  was  employed  sub- 
stantively to  dye  woollen  cloths  of  an  olive  green  colour; 
though  it  seems  now  to  be  rarely  used.  It  gave  cloth  an 
unpleasant  smell,  which  was,  however,  in  some  degree 
compensated,  by  the  certainty  with  which  the  cloth  was 
afterwards  thereby  preserved  from  the  depredations  of 
moths. 

Turmeric. 

Of  substantive  vegetable  yellows,  the  only  one  em- 
ployed in  Europe,  and  deserving  of  notice,  is  the  root  of 
the  Curcuma,  or  Turmeric;  which,  without  any  addition, 
yields  a  fine  bright  colour,  though  of  but  little  durability. 
Of  this  there  are  two  species,  the  Rotunda  and  the  Longa. 
The  latter  is  very  generally  employed  in  the  East  Indies, 
as  a  condiment  with  animal  food.  Tiie  former,  or  round 
root,  is  chiefly  cultivated  for  dyers'  use.  Loureiro,  after 
mentioning  both  species  as  growing  wild,  and  also  by 
cultivation,  in  China  and  Cochinchina,  adds,  concerning 
the  round,  "  radix  ista  non  est  esculenta:  ad  tingendum 
adhibetur  colore  quidempulchro^  sed  inconstante."  (Tom. 
i,  p.  9.) 

This  beautiful  colour  has  not  the  smallest  affinity  for 
any  metaUic  or  earthy  basis.  I  have  applied  solutions  of 
alumine,  tin,  iron,  and  all  the  other  metals,  in  spots^  to 
calico;  and  after  drying  and  rincing,  have  dyed  it  with 
turmeric,  which,  unlike  any  of  the  adjective  colouring 
matters,  was  imbibed  most  copiously  upon  the  parts 
which  had  received  no  basis  or  mordant;  and  the  colour 
being  exposed  to  the  sun  and  air,  it  did  not  prove  more 
fugitive  upon  these  parts,  than  on  those  to  which  alumine, 


206  Philosophy  of  Permanent  Colours. 

tin,  iron,  Stf^.  had  been  applied.  It  is  worthy  of  remark, 
also,  that  the  colour  itself  was  not  altered  by  any  basis. 

In  1793,  Mr.  Bay  ley,  who  was  extensively  engaged 
in  dyeing  silk  handkerchiefs  to  imitate  those  of  Iqdia,  in- 
formed me,  tliat  the  yellow  spots  in  these  handkerchiefs 
were  all  produced  by  a  tincture  of  Turmeric,  made  by  di- 
gesting six  pounds  of  the  powder  (of  Turmeric)  in  a  gallon 
of  malt  spirit,  and  afterwards,  by  a  press,  separating  three 
quarts  of  a  rich  tincture,  which  cost  about  four  shillings 
the  quart,  and  was  applied  topically,  and  without  thick- 
ening, to  parts  or  spots  of  the  silk  handkerchiefs,  which 
in  the  dyeing  had  been  reserved  white  by  the  usual  means. 

I  found  that  a  tincture  of  turmeric  obtained  in  this 
way,  and  gummed,  when  applied  topically  to  calico,  pro- 
duced a  beautiful  yellow,  which,  by  washing  with  soap, 
was  made  red;  but  being  well  rinced,  and  exposed  to 
atmospheric  air,  it  again  became  yellow;  and  in  this  way 
w^ould  bear  several  washings. 

Mr.  Clarkson,  in  his  Essay  on  the  Impolicy  of  the 
African  Slave  Trade,  relates  that  *^  a  gentleman,  resident 
upon  the  coast,  (of  Africa,)  ordered  some  wood  to  be  cut 
down,  to  erect  a  hut:  whilst  the  people  were  felling  it 
(continues  Mr.  C.)  he  was  standing  by,  and,  during  the 
operation,  some  juice  flew  from  the  bark  of  it,  and  stain- 
ed one  of  the  ruffles  of  his  shirt.  He  thought  that  the  stain 
would  have  washed  out;  but,  on  wearing  it  again,  he 
found  that  the  yellow  spot  was  much  more  bright  and 
beautiful  than  before,  and  that  it  gained  in  lustre  every 
subsequent  time  of  washing."  Pleased  with  the  disco- 
very, he  sent  home  a  small  sample  of  the  bark,  which 
*'  produced  a  valuable  yellow  dye,  far  beyond  any  other 
ever  in  use  in  this  country.''^ 

Mr.  Clarkson  adds,  that  this  gentleman  "  is  since  un- 
fortunately dead,  and  little  hopes  are  entertained  of  falling 
in  with  the  tree  again."  The  colour  mentioned  in  this 
account,  if  there  be  no  error  in  it,  must  have  been  of 


Philosophy  of  Permanent  Colours,  207 

that  kind  which  I  have  denominated  substantive,  as  ca- 
pable  of  being  fixed  by  dyeing,  &c.  without  the  aid  of 
any  aluminous  or  other  basis. 

M.  du  Pratz,  in  his  history  of  Louisiana,  also  men- 
tions a  tree,  or  shrub,  seldom  exceeding  the  thickness  of 
a  man's  leg,  the  wood  of  which,  he  says,  is  yellow,  and 
yields  a  juice  of  the  same  colour,  if  cut  in  the  sap.  Both 
the  wood  and  the  juice,  he  says,  have  a  disagreeable 
smell;  and  the  former  is  used  by  the  natives  for  dyeing, 
first  cut  into  small  pieces,  and  boiled  in  water,  into  which 
they  dip  feathers,  hair,  &c.  He  calls  it  ayac,  or  stinking 
wood;  and  as  he  mentions  nothing  of  the  use  of  alum,  or 
any  other  basis  or  mordant,  this,  if  his  account  be  accu- 
rate, must  also  be  a  substantive  colour.  I  fear,  however, 
that  the  information  of  persons,  not  particularly  acquaint- 
ed with  the  subject,  cannot  be  much  relied  upon  respect- 
ing the  natures  and  properties  of  dyeing  drugs. 

The  roots  and  bark  of  the  Berberis  vulgaris,  Linn,  or 
Barberry  shrub,  are  naturally  of  a  fine  yellow  colour, 
which  they  communicate  to  wool,  without  any  basis;  but 
it  has  not  the  smallest  degree  of  permanency  against  the 
action  either  of  air  or  soap.  This  shrub  indeed  furnishes 
a  remarkable  instance,  to  show  how  little  can  be  disco- 
vered respecting  the  colouring  properties  of  plants  from 
their  external  appearances.  A  similar  instance  lately  oc- 
curred to  me  in  the  wood,  bark,  and  root,  of  the  Zan- 
toxylum  clava  Herculis,  Linn,  (the  tooth-ach  tree,  or 
Japan  pepper  tree,)  every  part  of  which  is  strongly  co- 
loured of  a  most  beautiful  yellow;  but  having  procured 
some  of  it  for  trial,  I  could  extract  but  little  colour  from 
it,  notwithstanding  its  seeming  abundance  of  tingent  mat- 
ter; and  the  little  which  I  did  extract,  was,  like  that]  of 
the  Berberis,  utterly  incapable  of  forming  the  least  uniou 
with  any  basis,  or  of  resisting  the  action  of  air,  or  of 
soap,  in  any  degree. 


208  Philosophy  of  Permanent  Colours. 

In  a  note  to  p.  136,  I  have  referred  to  a  letter  from 
Dr.  Roxburgh,  mentioning  that  he  had  sent  from  India, 
for  trial  by  me,  a  parcel  of  **  the  coloured  tubes  of  the 
blossoms  of  nyctanthes  arbor  tristis,  Linn,  which  the 
Hindoos  employ  to  give  a  most  beautiful  but  fugitive 
orange  colour  to  cotton;"  and  I  found  that  these  tubes, 
by  mere  infusion,  even  with  cold  water,  yielded  such  a 
colour  as  Dr.  Roxburgh  has  described,  and  that  it  took 
readily  upon  cotton  and  silk,  by  mere  cold  maceration; 
but  it  had  no  affinity  or  attraction  for  alumine,  the  oxides 
of  tin,  iron,  or  any  other  basis,  or  mordant;  and  I  there- 
fore conclude,  that,  in  the  present  state  of  our  knowledge, 
there  is  no  probability  of  rendering  it  permanent;  though, 
as  a  substantive  colour,  it  resisted  the  sun  and  air,  for  a 
very  few  days,  on  calico,  and  for  a  week  on  silk,  and 
disappeared  gradually,  rather  by  losing  body,  than  by 
any  degradation  or  change  of  its  tint:  strong  muriatic 
acid  did  not  appear  even  to  weaken  the  colour,  but  it 
was  immediately  discharged  by  undiluted  nitric  acid, 
leaving  the  calico  perfectly  white:  oil  of  vitriol  had  less 
action  on  the  colour,  though  it  burned  holes  on  the  dyed 
cotton;  it  was  not  changed  by  washing  with  soap. 

Annotta. 
The  seeds  of  the  Bixa  Orellana,  Linn,  (growing  spon- 
taneously in  different  parts  of  Guiana,)  are  covered  with 
a  reddish  pulp,  which  is  collected  and  sent  to  Europe  in 
different  forms,  under  the  names  of  annotta,  arnotta,  and 
roucou.  It  is  principally  employed  for  dyeing  silk,  and 
sometimes  for  cotton;  though  its  colour,  by  all  the  ways 
and  means  of  applying  it,  hitherto  discovered,  is  so  fugi- 
tive, that  perhaps  it  would  be  better  if  it  were  never  em- 
ployed, even  for  dyeing  silk.  It  partakes  so  much  of  a 
resinous  nature,  as  to  dissolve  but  very  imperfectly  in 
w^atcr;  and  therefore  at  least  an  unequal  weight  of  potash 


Philosophy  of  Permanent  Colours.  209 

is  employed  to  render  it  soluble  in  that  vehicle,  and  after- 
wards the  silk  or  cotton  is  dyed  therein  without  any  alu- 
minous or  other  basis.*  The  colour  of  annotta  becomes 
less  red,  and  more  inclined  to  the  orange,  when  separated 
from  the  seeds  by  maceration,  in  water,  as  is  usually 
practised;  and  by  the  addition  of  potash,  it  is  made  to 
incline  still  more  to  the  yellow  hue.  This  last  change 
may,  however,  be  readily  overcome  by  adding  any  of  the 
different  acids  to  the  dyeing  liquor,  after  sufficient  colour 
has  been  taken  up,  by  the  silk  or  cotton  dyed  therein; 
and  afterwards  prolonging  the  dyeing  for  a  quarter  of  an 
hour:  argol  or  tartar  is  generally  prefen'ed  for  this  pur- 
pose, because  it  not  only  raises  the  colour,  but  seems  to 
render  it  a  little  more  fixed;  so  much  of  it  should  be 
used,  as  to  make  the  liquor  moderately  sour.  It  is  re- 
markable, that  though  the  colour  dyed  with  annotta  fades 
very  fast  by  exposure  to  air,  it  resists  soap,  and  the  ac- 
tion of  acids,  better  than  some  colours  which  are  much 
more  permanent.  And  it  certainly  affords  one,  among 
several  instances,  of  colours  which  decay  by  causes  ver}^ 
different  from  combustion;  because  linens  and  cottons, 
dyed  in  the  usual  ways  with  annotta,  suffer  less  than 
madder  colours  from  the  oxymuriatic  acid.  The  fresh 
pulp  of  the  Bixa  Orellana,  taken  immediately  from  the 
shrub  whilst  growing,  and  applied  to  cotton  without*  the 
addition  of  any  alkali,  seemed  to  afford  a  colour  more 
lasting,  and  approaching  nearer  to  the  red,  than  that  dyed 
from  the  pulp,  separated  by  maceration,  as  in  the  com- 
mon annotta.f  The  greatest  consumption  at  present  of 

*  The  liquid  sold  in  different  parts  of  the  town,  under  the  name 
of  «  Scott's  Nankeen  Dye,"  appears  to  be  nothing  but  an  alkaline 
solution  of  this  drug. 

t  M.  Leblond  has  proposed  (Ann.  de  Chim.  torn.  47)  to  separate 
the  colouring  matter  from  the  seeds  of  the  Bixa  Orellana,  simply 
by  washing  them  with  water,  and  after  precipitating  the  coloured 

Vol.  I.  2D 


210  Philosophy  of  Permanent  Colours*. 

this  article,  at  least  in  Great  Britain,  is,  in  giving  to 
cheese  a  kind  of  yellowish  orange  tint,  for  which  it  is 
very  suitable,  as  being  harmless,  and  nearly  tasteless. 

The  Lawsonia  inermis  of  Linn,  has  long  been  used 
throughout  India,  Persia,  Arabia,  Egypt,  and  in  many 
other  parts  of  Africa,  for  giving  a  reddish  stain  to  the 
nails,  lips,  &c.  It  is  the  Ligustrum  ^Egyptiacum  of 
Prosper  Alpinus,  and  the  Hinna  of  the  Arabians.  Sir 
William  Jones  relates,  that  being  at  the  island  of  Hin- 
zuan  or  Johanna,  and  observing  a  very  elegant  shrub, 
about  six  feet  high,  not  then  in  blossom,  he  learned,  that 
it  was  the  "  Hinna,"  of  which  he  had  read  so  much  in 
Arabian  poems.  **  Musa  (one  of  the  inhabitants,  says  he) 
bruised  some  of  the  leaves,  and  having  moistened  them 
with  water,  applied  them  to  our  nails,  and  the  tips  of  our 
fingers,  which  in  a  short  time  became  of  a  dark  orange 
scarlet."-:— NieuhofF  says,  they  prepare  the  tincture  by 
steeping  the  leaves  after  they  have  been  rubbed  small 
upon  a  marble  stone,  in  fair  water,  mixed  with  a  small 
quantity  of  lime." — "  With  this  (continues  he)  the 
Turks  and  Persians  also  dye  their  horses'  tails."  This 
shrub,  according  to  Adanson,  is  called  foudenn,  by  the 
negroes  of  Senegal,  where  it  is  used,  both  by  the  men 
and  women,  to  give  their  nails  a  red  stain,  which  lasts 
until  the  substance  of  the  nails  changes  by  growth.  As 
the  colour  of  this  shrub  requires  no  kind  of  basis  or  mor- 
dant, it  must  naturally  belong  to  the  class  of  substantive 
colours,* 

matter  by  lemon  juice  or  vinegar,  to  render  it  dry  and  hard  by 
evaporation;  and  Vauquelin  having  made  experiments  with  the 
colour  so  prepared,  concludes  it  to  be  worth,  at  least,  four  times 
as  much  as  the  common  annotta. 

*  This  account  of  the  Lawsonia  inermis,  was  published  in  1794, 
oefore  I  had  seen  any  of  it.  But  in  1801,  my  son,  being  in  Egypt, 
^  physician  to  the  British  army  there)  sent  me  several  packages 


Philosophy  of  Permanent  Colours,  211 

I  lately  received  a  few  ounces  of  small  seeds,  inclosed 
in  a  flea-coloured  husk,  but  without  any  information  re- 
specting the  plant  on  which  they  grew.  They  were 
brought  from  the  coast  of  Barbary,  where,  as  I  was  in- 
formed, they  are  used  in  dyeing  red  or  pink  colours.  In 
two  or  three  small  trials  which  I  made  with  them  on  silk, 
they  appeared  to  possess  a  substantive  colouring  matter, 
similar  in  some  respects  to  that  of  saiflower.  At  first  I 
thought  they  might  be  the  seeds  of  the  gardenia  florida, 
which,  according  to  the  accounts  of  Mr.  James  Cunning- 
ham, who  formerly  travelled  into  different  parts  of  the 
East  Indies  in  pursuit  of  natural  curiosities,  the  Chinese 
employ  for  dyeing  scarlet ^  under  the  name  of  unkL^  X 

of  the  leaves,  dried  and  powdered;  and  by  the  experiments  which 
I  have  since  made  with  this  powderj  I  am  inclined  to  think,  that  it 
ought  to  be  removed  from  its  present  arrangement,  and  placed 
among  the  adjective  colours.  For  though  great  quantities  of  it  are 
employed  substantively  as  a  dye,  it  has  a  decided  affinity  for  the 
basis  of  alumine,  and  that  of  iron,  giving  with  the  former  a  perma- 
nent orange-brown  to  calico,  and  with  the  latter  a  brownish  black. 

Sonini  represents  the  dried  leaves  of  this  plant,  as  a  valuable 
orange  or  reddish  dye,  and  says,  that  1 4  or  15  ships  were  annually 
loaded  with  them  at  Alexandria,  and  sent  to  Constantinople,  Smyr- 
na, and  Salonica,  whence  a  part  was  exported,  particularly  to  Ger- 
many, and  there  used  "  in  dyeing  furs,  and  the  preparation  of 
leather." 

Another  species,  which  is  thorny^  possesses  the  same  tingent 
property.  Hasselquist  says,  the  practice  of  dyeing  the  nails  with 
the  Lawsonia  spinosa  (alhenna,)  is  so  ancient  in  Egypt,  that  he  has 
seen  the  nails  of  mummies  dyed  therewith.  He  adds,  that  the  pow- 
dered leaves  are  annually  exported  in  great  quantities. 

Loureiro  says,  of  the  Lawsonia  spinosa,  "  foliis  contritis  admixta 
calce,  utuntur  Cochinchinenses,  ad  tingendos  ungues  colore  ruber- 
rimo:  qui  mos  pro  elegantia  invaluit  non  solum  apud  alios  populos 
Indianos,  sed  etiam  apud  Turcas,  Persas,  ^Ethyopes."  Tom.  i.  p. 
229. 

*Dr.  Plunkenet,  in  his  Amaltheum,  page  29,  says,  "  Semina 
tinctoribus  inserviunt  iis  enim  ab  indigenis  Sinensibus  optime 
tingitur  nobilis  ille  color,  quern  escarlatinum  nostrates  vocant,  ut 


212  Philosophy  of  Permanent  Colours, 

found,  however,  that  this  could  not  be  the  case,  as  the 
seeds  of  the  gardenia  grow  inclosed,  several  of  them  in 
one  common  capsule,  involved  in  a  rich- coloured  muci- 
laginous substance;  whereas  the  Barbary  seeds  evident- 
ly grew  without  any  such  inclosure.  I  cannot  discover 
whether  the  seeds  of  this  gardenia,  or  the  mucilage  sur- 
rounding them,  ought  to  be  considered  as  a  substantive 
or  an  adjective  colouring  substance;  all  accounts  being 
defective  in  this  respect.* 

Safflower. 
This  is  the  Carthamus  tinctorius,  Linn,  which  is  cul- 
tivated in  the  southern  parts  of  Europe,  Egypt,  &c.  and 
also  in  the  East  Indies,  whence  considerable  quantities 
of  it  have  been  lately  imported  to  Great  Britain.  There 

nos  monuit  vir  multiplicis  industriae  atque  indefessi  laboris  hac  in 
parte,  D.  Jacobus  Cunninghamus." 

*  When  the  late  Sir  George  Stanton  returned  from  the  embassy 
to  China,  in  which  he  was  associated  with  Lord  Macartney,  he 
gave  me  some  yards  of  a  cotton  cloth,  which  had  been  dyed  scar- 
let, and  probably  from  the  gardenia  florida,  (now  called  cape  jas- 
mine in  this  country.)  It  was  one  of  the  articles  mentioned  by  Mr. 
Barrow  in  the  following  words,  viz.  ''  among  some  of  our  presents 
ivere  2i\?>o  pieces  of  a  beautiful  scarlet'*  (P.  560.)  The  colour  of  the 
cloth  so  given  to  me,  certainly  approached  nearer  to  the  cochineal 
scarlet  than  any  which  I  have  seen  dyed  on  cotton,  in  Europe,  and 
it  seemed  to  be  of  a  resinous  nature,  dyed  substantively  without 
any  basis,  and  capable  of  bearing  exposure  for  a  reasonable  time 
to  the  sim  and  air,  but  liable  to  be  in  a  considerable  degree  dis- 
charged by  washing  with  soap.  Concentrated  oil  of  vitriol  had  but 
little  effect  upon  this  scarlet.— Strong  muriatic  acid  changed  it  to 
an  orange;  and  double  aqua  fortis  made  it  yellow.  So  that  it  was 
much  less  injured  by  these  acids,  than  colours  vastly  more  durable 
are  known  to  be. 

Loureiro  moreover  mentions  another  species  of  this  genus,  viz. 
gardenia  grandiflora,  whose  succulent  berries,  recently  gathered, 
are,  as  he  says,(tom.  i.  p.  147,)  employed  to  dye  silk  of  an  elegant 
red  colour. 


Philosophy  of  Permanent  Colours.  215 

are  two  varieties  of  this  plant,  one  of  which  is  distin- 
guished by  having  much  broader  leaves  than  the  other. 
Berthollet  mentions  the  narrow- leaved  as  that  which  is 
cultivated  in  Egypt,  whence  considerable  quantities  of  it 
are  from  time  to  time  exported.*  It  is  the  flower  only 
of  this  plant  which  is  employed  in  dyeing,  and  which 
affords  two  sorts  of  colouring  matter,  one  soluble  in  wa- 
ter, and  producing  a  yellow  of  but  little  beauty,  when 
dyed  adjectively,  on  an  aluminous  basis;  the  other  is 
resinous,  and  best  dissolved  by  the  fixed  alkalies:  it  is 
this  last  which  alone  renders  safflower  valuable  in  dyeing, 
as  it  affords  a  red  colour,  exceeding  in  delicacy  and 
beauty,  as  it  does  in  costliness,  any  which  can  be  ob- 
tained, even  from  cochineal,  though  much  inferior  to  the 
latter  in  durability. 

To  obtain  this  red  colour  of  safflower,  it  should  be 
tied  up  in  a  linen  bag,  and  subjected  to  maceration  and 
pressing  in  clean  running  water,  until  all  the  yellow  co- 
louring matter  is  dissolved,  and  washed  away,  and  the 
flowers  which  were  previously  yellow,  are  made  red  by 
an  abstraction  of  this  yellow  colour.  This  being  done, 
the  flowers  are  again  to  be  macerated  in  a  solution  of 
clean  soda,  in  quantity  sufficient,  and  only  sufficient, 
completely  to  dissolve  and  extract  the  resinous  or  beau- 
tiful red  colouring  matter;  which  is  to  be  separated  by 
draining,  and  the  application  of  more  water  to  the  resi- 
duum, until  the  whole  is  abstracted  and  collected  for 
use.  To  fit  this  colouring  matter  for  dyeing,  the  soda  by 
which  it  was  extracted  is  to  be  neutralized  by  an  acid; 
and  for  this  purpose  the  citric  acid  is  generally  preferred 
to  all  others,  and  more  especially  that  which  is  contained 
in  lemons,  or  limes  begiiming  to  rot  or  spoil;  or  in  their 

*  Niebuhr  says,  there  are  ten  varieties  of  safflower  cultivated  in 
Egypt,  and  that  the  quantity  annually  produced,  commonly  amount- 
ed to  between  fifteen  and  eighteen  thousand  quintals. 


214  Philosophy  of  Fermanent  Colours, 

juice,  when  it  has  been  kept  some  months  in  casks,  and 
the  mucilage  has  suffered  a  partial  decomposition.  Next 
to  the  citric  acid,  that  of  tamarinds,  and  of  tartar,  are 
thought  moft  suitable;  though  Bergman  has  recommend- 
ed the  sulphuric,  as  next  to  the  citric,  if  it  be  not  used  in 
excess.  But  Scheffer  pretends  that  the  acid  juice  of  the 
berries  of  the  pyrus  acuparia,  or  mountain  ash,  produces 
a  better  and  more  lasting  colour  than  even  the  citric 
acid. 

The  colour  of  safflower  will  not  bear  the  action  of 
soap,  nor  even  that  of  the  sun  and  air,  for  a  long  time; 
and  being  more  costly  than  even  the  colour  of  cochineal, 
it  is  principally  employed  for  imitating  upon  silk  the  fine 
scarlet  (ponceau  of  the  French)  and  rose  colours,  which 
are  dyed  with  cochineal  upon  woollen  cloth.  Beckman 
pretends  that  by  preparing  cotton  as  for  the  Turkey  red, 
and  dyeing  it  with  safflower,  the  colour  was  rendered 
much  more  durable,  than  it  is  by  the  ordinary  process; 
but  in  this  way  it  will  cost  so  much,  and  after  all  prove 
so  inferior,  in  point  of  durability ^  to  the  Turkey  red,  that 
this  method  of  employing  safflower,  does  not  seem  likely 
to  be  ever  adopted. 

The  fine  rose  colour  of  safflower,  extracted  by  crys- 
tallized soda,  and  precipitated  by  citric  acid,  and  then 
slowly  dried  in  the  shade,  being  afterwards  finely  ground 
with  the  purest  talc,  produces  the  beautiful  paint  by 
which  ladies  give  to  their  cheeks  the  bloom  of  youth  and 
health,  and  which  die  French  distinguish  from  carmine 
by  the  name  of  *'  rouge  vegetaleJ*"* 

Aloes* 

M.  Fabroni,  in  a  memoir  printed  in  the  25th  volume 

of  the  Annales  de  Chimie,  has  stated,  that  the  almost 

colourless  juice  of  the  aloe  succotrina  angustifolia,  by 

exposure  to  atmospheric  air,  assumed  a  fine  purple  co- 


Philosophy  of  Permanent  Colours.  215 

lour  from  an  absorption  of  oxygene,  and  that  he  had 
dyed  a  beautiful  and  lasting  purple  with  it  upon  silk^ 
without  any  mordant  or  basis  whatever;  and  in  the  68th 
volume  (p.  165)  of  the  same  work,  M.  M.  Bouillon 
Lagrange^  and  Vogel,  have  asserted,  that  nitric  acid, 
heated  with  powdered  aloes,  produced  a  beautiful  yellow 
powder,  which,  on  being  mixed  with  water,  gave  to  die 
latter,  a  magnificendy  rich  purple  colour:  that  a  single 
atom  was  sufficient  to  colour  a  large  portion  of  water, 
and  that  the  colour  was  so  permanent,  that  when  applied 
to  the  fingers,  the  stain  continued  several  days,  especially 
if  a  little  alkali  had  been  previously  mixed  with  the 
powder. 

Encouraged  by  these  statements  I  was  induced,  when 
this  volume  was  nearly  ready  for  a  second  impression,  to 
rub,  in  a  glass  mortar,  some  of  the  best  Barbadoes  aloes, 
and  pour  upon  it  a  little  strong  nitric  acid,  to  which, 
after  it  had  been  mixed  with  the  aloes,  I  added  three  or 
four  times  as  much  water;  and  with  this  mixture  farther 
diluted,  I  the  next  day  dyed  some  pieces  of  white  broad 
cloth  and  calico:  the  latter  took  only  a  sort  of  tobacco 
colour;  but  the  cloth  soon  exhibited  a  rich,  though 
brownish,  purple,  of  considerable  brightness,  and  which, 
after  exposure  to  the  sun  and  air  during  all  the  month  of 
July  (1812,)  had  suffered  no  change,  excepting  that  it 
seemed,  perhaps,  half  a  shade  darker  and  fuller  than  at 
first.  I  conclude  therefore  that  this  colour  is  eminently 
durable.  It  had,  however,  too  much  of  the  chocolate 
brown  in  its  composition  to  be  deemed  a  beautiful  pur- 
ple. I  tried  a  similar  mixture,  with  a  nitro  muriate  of 
tin,  and  with  alum,  but  neither  of  them  appeared  to  im- 
prove the  colour  in  any  way.  I  also  tried  it  with  sulphate 
of  iron,  which  produced  no  change. 

How  far  it  might  be  practicable  to  render  this  aloetic 
colour  stricdy  a  fine  purple,  and  how  far,  in  point  of 


216  Philosophy  of  Permanent  Colours. 

cheapness,  it  would  be  advantageous  for  common  use, 
are  questions  which  I  am  not  yet  able  to  answer.  Per- 
haps the  more  common  Barbadoes  aloes,  might  answer 
as  well  as  that  with  which  my  experiments  were  made. 
I  mean  soon  to  ascertain  this  fact. 

Aloes  powdered,  and   mixed  with  strong  sulphuric 
acid,  produced  only  a  snuff  colour  upon  broad  cloth, 
and  with  muriatic  acid,  it  produced  only  a  lighter  brown;  . 
the  purplish  colour  before  mentioned,  is  therefore  an 
effect  of  the  nitric  acid  alone. 

Orchall  and  Cudbear, 
The  Linnean  genus  of  Lichen,  belonging  to  the  natu- 
ral order  of  algae,  contains  numerous  species,  of  which 
several,  after  being  macerated  with  ammonia  or  volatile 
alkali,  afford  beautiful  violet,  purple,  and  crimson,  sub- 
stantive dyes;  of  these  the  most  valuable  is  obtained  from 
the  lichen  roccella,  Linn.,  which  in  the  quantity,  vivacity, 
and  durability  of  its  colour,  excels  every  other  species  of 
lichen;  though  unfortunately  even  this  cannot  be  deemed 
a  fast  or  permanent  dye.  Dr.  Dillenius  has  given  an  ac- 
curate figure  and  description  of  it  in  his  excellent  and 
elaborate  >'  Hisioria  Muscorum,"  Oxonii  1741.  4to.  p. 
120,  tab.  17,  fig.  39,  under  the  name  of  coralloides 
corniculatum  fasciculare  tinctorium,  fusci  teretis  facie." 
And  he  thinks,  with  reason,  that  it  is  the  identical  totov- 
t;ov  (pujcos-,  or  alga  marina  of  Theophrastus,  and  the  Kux^i^ 
of  Dioscorides,  mentioned  by  them  as  being  in  great  use 
and  estimation  for  dyeing  wool,  of  a  colour  more  beauti- 
ful, when  first  dyed,  even  than  the  Tyrian  purple.*  Pliny 
also  mentions  it,  as  I  have  already  noticed  at  p.  93^  and 
in  his  26th  book,  chapter  10,  he  calls  it  *'Phycos  tha- 
lassion;"  "  id  est  fucus  marinus;"  adding,  that  it  serves 

*  Theophrast.  Hist.  Plant,  iv.  c.  7.  pi  82.  Ed.  Heinsii.  Dioscorid. 
Lib.  iv,  c.  95. 


Philosophy  of  Permanent  Colours,  217 

as  a  ground  for  the  shell  purple,  "  qui  conchy  His  subster- 
nitur:"  and  in  his  32d  book,  chapter  6th,  he  mentions  it 
again  as  one  of  the  "  algae  maris,"  of  which,  says  he, 
there  are  several  kinds,  and  among  them  that  of  Crete  is 
most  commended,  &c.  ''  Laudatissima  quae  in  Creta  in- 
sula juxta  terram  in  petris  nascitur;  tingendis  etiam  lanis 
ita  color  em  alligansy  ut  elui  postea  non  potest,"  He  was 
however  greatly  mistaken  in  thus  supposing  that  it  con- 
tributed to  render  other  dyes  more  fixed  or  lasting. 

After  all  knowledge  of  the  use  of  this  lichen  had  (in 
common  with  arts  and  sciences)  been  lost  for  several 
centuries  in  the  west  of  Europe,  it  was  restored  at  Flo- 
rence early  in  the  14th  century,  by  a  Florentine,  de- 
scended from  a  German  named  Ferro,  or  Frederigo, 
who  having  resided  some  years  in  the  Levant,  and  ac- 
quired information  respecting  the  properties  of  this  lichen, 
returned  to  Florence,  and  there  introduced,  and  exclu- 
sively enjoyed,  the  use  of  it  in  dyeing,  for  some  years; 
and  acquiring  great  wealth,  became  the  founder  of  one 
of  the  principal  Florentine  families,  who  took  the  name 
of  Oricellarii  (afterwards  abbreviated  to  Rucellarii  and 
Rucellai,)  from  the  name  of  Oricello,  by  which  this 
commodity  was  afterwards  distinguished  in  Italy:  and 
the  Italians  having  thus  become  acquainted  with  the 
preparation  and  uses  of  this  lichen,  engrossed  for  a  cen- 
tury all  that  could  be  procured  of  it  among  the  islands 
of  the  Archipelago,  and  on  the  shores  of  the  Mediterra- 
nean, until  the  discovery  of  the  Canary  islands  (which 
had  likewise  been  lost)  in  1402,  by  John  de  Bethen- 
court,  a  Norman,  relieved  the  other  nations  of  Europe 
from  their  dependence  upon  Italy  for  this  commodity.* 

*  I  have  now  before  me  the  scarce  "  Histoire  de  la  premiere  de- 
couverte  et  conquete  des  Canaries,  &c."  by  this  Bethencourt,  (de- 
scribed as  chamberlain  to  the  French  king  Charles  VI.)  stated  to 
have  been  written  by  two  priests  (Boutier  and  Le  Verrier)  who 
Vol.  I.  2  E 


218  Philosophy  of  Permanent  Colours. 

At  a  much  later  period  (i.  e.  about  1730)  the  orchella 
was  discovered  growing  abundantly  and  luxuriantly  at 
the  Cape  dc  Verd  islands;  where  it  had  been  left  to  ac- 
quire full  maturity,  unmolested,  and  was  found  to  be 
much  larger  and  richer  in  colouring  matter,  than  any 
which  had  been  previously  known.  The  quantity  had 
however  been  considerably  diminished,  when  Wadstrom 
was  there  about  half  a  century  afterwards.  The  labour 
of  gathering  the  orchella  then  cost,  as  he  informs  us, 
about  five  shillings  sterling  the  quintal,  and  the  medium 
price  at  Porto  Praya,  was  about  3000  reas,  (or  18.S.  6d. 
sterling;)  but  when  carried  to  Lisbon,  it  sold  for  19,200 
reas,  more  than  six  times  as  much.  It  often  sells  at  Lon- 
don for  300/.  sterling  per  ton,  and  sometimes  for  more 
than  1000/. 

Ray,  (Hist.  Plant,  i.  p.  74,)  has  given,  from  Imperatus, 
a  short  account  of  the  preparation  of  Orchella  for  dyeing; 
and  Micheli  has  since  published  one,  which  is  more  cir- 
cumstantial, and  probably  conformable  to  the  practice  of 
the  Florentines.  The  means  employed  were  human  urine, 

were  in  his  suite,  and  published  by  "  Galien  de  Bethencourt,  Con- 
seillier  du  Roi,"  in  the  parliament  of  Rouen,  (printed  at  Paris  in 
1630,)  in  several  parts  of  which,  mention  is  made  of  this  commo- 
dity, particularly  at  p.  130,  where,  in  describing  the  productions  of 
these  islands,  I  find  these  words:  '*  Et  y  croit  une  graine  qui  vaut 
beaucoup,  qui  on  appelle  orsolle;  elle  sert  a  teindre  drap  ou  autre 
choses,  et  est  la  meilleure  graine  que  Ton  sache  trouver  en  nul 
pais  pour  la  condition  d'icelle;  et  si  cette  isle  est  une  fois  conquisc 
et  mise  a  la  foi  chretienne^  icelle  graine  sera  de  grand  valeur  an 
sieur  du  pais;"  and  in  a  note  the  following  explanation  is  subjoin- 
ed: "  Orsolle  graine  a  teindre  de  grand  prix,  oriocola  ou  oricola, 
dont  sefait  grande  trafic  par  tout."  Afterwards,  at  p.  180,  I  find, 
that  Bethencourt,  among  other  regulations,  prohibited  all  persons 
from  dealing  in  this  commodity,  meaning  to  resei-ve  the  profits  of 
it  exclusively  to  himself,  as  the  kings  of  Spain  have  since  done  in 
the  islands  of  Canary,  Teneriffe,  and  Palma.  The  Canaries  have 
since  annually  produced  about  2,600  quintals  of  orchella. 


Philosophy  of  Permanent  Colours.  219 

and  either  potash  or  soda,  with  which  the  powdered  lichen 
was  mixed,  macerated  and  fermented  (in  close  wooden 
vessels)  for  several  weeks,  until  the  resinous  colouring 
matter,  by  combination  with  the  ammonia  of  the  urine, 
had  been  sufficiently  evolved  and  dissolved:  after  which, 
it  was  preserved  in  a  moist  state  in  tight  casks,  sprin- 
kling the  surface,  when  necessary,  with  urine  or  lime 
water,  until  wanted  by  the  dyer.  Lime  has  since  been 
substituted  for  potash  and  soda,  as  several  other  species 
of  lichen  have  been  for  the  rocella,  or  orchella,  though 
none  is  of  equal  value  or  utility.  One  of  the  best  of  these 
substitutes  probably  is  a  lichen,  which  Imperatus  has 
described  and  figured,  (Hist.  Nat.  xxvii.  cap.  11,)  as 
growing  on  rocks  near  the  sea  in  Candia,  and  there 
called  rubicula;  it  is  nearly  related  to  the  orchella,  and 
frequently  mixed  with  it.  Linnaeus  has  named  it  lichen 
fuciformis.  It  grows  also  in  the  East  Indies. 

The  French  have  for  several  centuries  employed  in 
this  way,  a  species  of  lichen  called  by  them  perelle  from 
a  corruption  of  the  word  pierre,  (stone),  it  being  com- 
monly found  adhering  to  volcanic  stones,  or  productions; 
and  it  has  been  generally  supposed  and  stated  to  be  the 
lichen  parellus  of  Linn.,  but  it  appears  certain,  from  a 
"  Memoire"  by  M.  Cocq,  just  pubUshed  in  the  81st  vo- 
lume of  the  Annales  de  Chimie,  that  this  is  a  mistake; 
that  in  Auvergne,  where  this  lichen  is  principally  gather- 
ed, the  true  lichen  parellus  of  Linnaeus  is  called  la  pom- 
melee,  and  that  this  is  constantly  rejected  by  the  persons 
employed  to  gather  the  perelle^  as  being  unfit  for  their 
purpose:  and  indeed  M.  Cocq  found,  by  suitable  trials, 
that  the  lichen  parellus  of  Linn,  would  only  yield  "  un 
chamois  rougeatre."  And  he  asserts  most  positively, 
that  the  moss  collected  and  employed  to  produce  I'or- 
seille  d' Auvergne,  (sometimes  also  called   orseille  de 


220  Philosophy  of  Permanent  Colours, 

terre)  is  the  variolaria  orcina  of  Acharius,*  (which  Dr. 
Westring  has  mentioned  as  affording  a  beautiful  colour;) 
that  this  is  generally,  and  invariably  denominated  perelle 
in  Auvergne,  and  that,  when  prepared  in  the  usual  way, 
it  afforded  *'  la  belle  et  vive  couleur  rouge  amarante^  qui 
les  teinturiers  du  pays  en  tirent."  It  sells  he  says  in  Au- 
vergne, for  between  12  and  24  sols  the  pound,  and  a 
labourer  may  gather  four  pounds  daily,  M.  Chaptal  says, 
the  EngHsh  used  to  obtain  it  on  the  coast  of  Italy,  (pro- 
bably at  the  isle  of  Elba.) 

M.  Cocq  gives,  in  the  same  memoire,  a  particular  ac- 
count of  the  process  by  which  the  perelle  is  prepared  for 
dyers'  use,  at  Clermont;  he  having  been  extensively  en- 
gaged in  that  business  for  several  years.  It  appears  that 
wooden  troughs  are  employed  as  usual  to  macerate  and 
ferment  the  perelle:  that  these  troughs  are  commonly 
about  six  feet  in  length,  two  or  three  in  breadth  (but 
narrowest  at  bottom,)  and  about  two  feet  in  depth;  and 
that  to  each  trough  a  cover  is  exactly  fitted,  so  that  it 
may  retain  as  much  as  possible  of  the  volatile  alkali  of 
the  (human)  urine;  of  which  240lbs.  are  commonly  em- 
ployed for  every  2001bs.  of  the  perelle;  this  last  being  the 
quantity  usually  allotted  for  each  trough,  and  which  it 
will  about  half  fill.  In  such  a  trough  the  perelle  and  urine 
are  to  be  well  mixed,  and  afterwards  stirred  every  three 
hours,  during  two  days  and  nights,  taking  off  the  cover 
only  as  often,  and  as  long  as  is  necessary  for  the  stirring. 
On  the  third  day  lOlbs.  of  sifted  and  slack  lime  are  to  be 
added,  and  well  mixed,  together  with  a  quarter  of  a 
pound  of  arsenic,  and  as  much  alum.  The  workmen  are 
to  avoid  the  fumes  of  the  arsenic  as  much  as  possible, 
for  some  hours  after  its  admixture. — But  when  there  is 
no  longer  any  danger  from  these  fumes,  the  stirring  is  to 

*  Meth.  Lich.  suppf.  p.  6. 


Philosophy  of  Permanent  Colours.  221 

be  repeated  several  times,  once  each  quarter  of  an  hour, 
and  afterwards  at  the  intervals  of  half  an  hour,  until  the 
fermentation  is  established;  after  which  the  mixture  need 
only  to  be  stirred  often  enough  to  hinder  the  formation 
of  a  crust  on  the  surface,  which,  by  obstructing  the  fer- 
menting process,  would  hinder  a  complete  formation  and 
evolution  of  the  colour.  When  the  fermentation  has  sub- 
sisted 48  hours,  it  commonly  begins  to  slacken,  and  is 
then  to  be  excited  by  an  addition  of  21bs.  more  of  sifted 
lime,  and  the  stirring  repeated  once  every  hour  until  the 
fifth  day,  when  the  frequency  of  stirring  may  afterwards 
be  gradually  diminished.  On  the  eighth  day,  there  will 
be  a  considerable,  but  not  a  complete  manifestation  of 
the  colour;  and,  therefore,  the  operation  is  to  be  con- 
tinued a  fortnight  longer,  (stirring  the  mixture  at  inter- 
vals of  six  hours;)  and  even  after  this,  it  is  commonly 
thought  safest  and  best  to  extend  the  process  another 
week,  making  in  all  a  lunar  month;  though  when  the 
perelle  is  rather  deficient  in  colouring  matter,  three  weeks 
will  fully  suffice. 

The  colouring  matter  so  produced,  is  afterwards  to  be 
kept  moist  in  closed  casks,  in  which  it  will  improve 
during  the  first  year;  remain  stationary  during  the  second, 
and  begin  to  decline  in  quality  afterwards.  When  the 
volatile  alkali  has  evaporated,  the  orseille  (as  it  is  called 
when  so  prepared)  acquires  an  agreeable  violet  smell, 
and  by  simple  boiling  it  will,  says  M.  Cocq,  dye  upon 
cloth  **  un  amarante;''^  and  with  longer  boiling  "  un 
amar ant e  f once y  I  shall  presently  offer  some  observa- 
tions upon  this  process,  when  treating  of  the  preparation 
of  Cudbear  in  this  country. 

During  many  years,  perhaps  several  centuries,  the  in- 
habitants of  Sweden,  Scotland,  Ireland,  Wales,  and  some 
of  the  northern  parts  of  England,  have  employed  different 
species  of  lichen,  macerated  with  urine,  in  their  domestic 


222  Philosophy  of  Permanent  Colours, 

dyeing. — One  of  these,  the  lichen  omphalodes,  Linn, 
has  been  commonly  called  cork,  corker,  and  arcel;  and 
in  Wales  kenkering;  and  it  gave  a  kind  of  dark  crimson 
to  wool  and  woollen  stuffs.  It  is  the  lichenoides  saxatile 
tinctorum  foliis  purpureis  of  Ray.  (Synops.  p.  74,  No. 
70.)  Linnaeus  says,  (in  his  Flora  Lapponica)  that  an  im- 
mense  quantity  of  this  lichen  grows  on  the  island  of 
Aland,  in  the  Baltic. 

The  lichen  calcareus,  Linn.,  or  lichenoides  tartareum 
tinctorium  candidum  tuberculis  atris  of  Dillenius,  (p. 
128)  which  grows  exclusively  on  limestone  rocks,  pos- 
sesses similar  properties,  and  has  been  long  used  in  the 
same  way,  by  the  people  of  Wales,  the  Orkneys,  &c. 

Nearly  similar  colours  may  be  obtained  from  several 
other  species  of  this  genus,  (by  maceration  with  lime  and 
urine),  particularly  the  lichen  saxatilis,  Linn,  (or  lichen 
de  roche  of  La  Marck,  Flor.  Franc,  p.  78);  the  lichen 
caperatus,  Linn.,  lichen  pustulatus,  Linn.,  lichen  argen- 
tatus,  Linn,  (called  cadlog,  and  kengevin,  in  Wales);  li- 
chen stygius  imbricatus,  &c.  Linn.,  lichen  nivalis,  Linn., 
lichen  deustus,  Linn.,  lichen  fistulosus  of  Hudson,  and 
lichen  muscorum  of  Hoffman;  which,  Kalm  says,  the 
Pennsylvanians  macerate  three  months  in  urine,  and 
then  dye  with  it  a  beautiful  red  colour. 

But  the  most  important  of  all  the  lichens  produced  in 
the  northern  parts  of  Europe,  seems  to  be  the  lichen  tar- 
tareus,  Linn.,  a  crustaceous  moss,  growing  commonly 
on  lime-stone  rocks,  in  Sweden,  Scotland,  the  north  of 
England,  &c.  It  is  the  lichenoides  tartareum  farinaceuoi 
scutellarum  umbone  fusco  of  Professor  Dillenius  (p.  132.) 
Linnaeus  mentions,  (Iter  West-Goth.  p.  170)  that  the 
people  of  West- Gothland  prepare  a  beautiful  crimson  dye 
from  this  lichen,  which,  under  the  name  of  byttelet,  is 
used  all  over  Sweden;  and,  besides  this  use,  Dr.  West- 


Fhilosophy  of  Permanent  Colours.  223 

ring  computes,  that  about  one  hundred  and  thirty  tons  of 
it  have  been  annually  exported  from  that  kingdom,  since 
the  year  1770.  This  is  the  lichen,  with  which  a  purple 
or  violet-coloured  powder  is  prepared  in  Great  Britain, 
and  sold  under  the  name  of  cudbear;  a  name  given  to  it 
by  the  late  Dr.  Cuthbert  Gordon,  who,  having  obtained 
a  patent  for  this  preparation,  chose,  in  this  way,  to  con- 
nect it  with  his  own  first  name,  which  had  been  the 
maiden-name  of  his  mother. 

Having  never  seen  Dr.  Gordon's  specification  of  his 
invention,  I  do  not  know  the  peculiar  novelty  by  which 
it  was  distinguished — perhaps  it  may  have  been  that  of 
giving  the  preparation  a  dry  instead  of  a  wet  form;  or 
the  circumstance  of  employing  ammonia,  obtained  by 
distillation  from  urine,  instead  of  the  urine  itself^  to  ex- 
tract and  raise  the  colour  of  the  lichen;  a  change  which, 
whether  made  by  him  or  not,  certainly  was  a  considera- 
ble improvement,  as  urine  contains  many  other  matters, 
which,  at  best,  are  but  an  useless  incumbrance  to  the 
volatile  alkali. 

At  the  proper  times  and  places,  one  person  may  col- 
lect twenty  or  thirty  pounds  weight  of  this  lichen  daily; 
but  it  should  be  allowed  five  years  growth  before  it  is 
gathered.  It  commonly  sells  at  the  port  of  London  for 
twenty  pounds  the  ton:  but,  to  prepare  it  for  use,  it  must 
be  washed  and  dried;  and  by  these  operations  the  weight 
is  commonly  diminished  one  half,  and  the  price,  in  effect, 
doubled.  It  is  macerated  and  stirred  in  wooden  troughs 
or  vessels  with  covers,  as  is  practised  with  the  perelle 
at  Clermont,  in  Auvergne,  only  substituting  an  aqua 
ammonia^  obtained  by  distilling  human  urine,  that  of 
graminivorous  animals  being  deficient  in  the  volatile 
alkali;  the  purity  of  which  seems  to  be  of  more  impor- 
tance to  the  beautv  of  the  colour,  than  is  commonly  sup- 


224  Philosophy  of  Permanent  Colours, 

posed.*  I  have  prepared  this  colour  several  times,  and 
am  convinced,  that  the  alum,  mentioned  by  M.  Cocq, 
is  completely  useless — and  that  the  arsenic  is  both  use- 
less and  dangerous;  indeed,  I  believe  the  latter  is  not 
employed  in  this  country.  It  seems  to  me,  also,  that  much 
labour  in  stirring,  and  much  waste  of  volatile  alkali  might 
be  saved,  by  employing  hogsheads  instead  of  fixed 
troughs  or  w^ooden  vessels.  The  lichen  ground  in  a  mill, 
properly  constructed,  might  be  put  with  the  aqua  am- 
monia into  the  bung-hole,  purposely  made  a  little  larger 
than  common,  and  the  bung  being  applied  and  secured^ 
so  as  to  hinder  any  leakage,  the  hogsheads  might  be  roll- 

*  Of  this  fact  a  decisive  proof  lately  occurred  to  mc,  in  conse- 
quence of  an  application  from  certain  manufacturers  of  cudbear,  in 
the  neighbourhood  of  London,  who  complained,  that  they  were 
unable  to  obtain  more  than  half  the  usual  price  of  that  article  for 
the  produce  of  their  own  manufactory:  and,  being  unable  to  disco- 
ver the  cause  of  its  manifest  inferiority,  they  requested  my  assist- 
ance to  remove  its  defects.  For  this  purpose,  they  supplied  mc 
with  parcels  of  the  lichen  which  they  had  commonly  employed, 
b^th  in  its  washed  and  unwashed  state;  and  also  with  some  of  their 
aqua  ammonia,  and  I  soon  satisfied  myself  that  the  latter  had  alone 
occasioned  the  defects  of  which  they  complained.  In  making  use 
of  it,  I  found,  that  after  the  predominant  odour  of  the  ammonia  was 
a  little  dissipated,  another  became,  and  remained  prevalent,  which 
was  extremely  offensive,  and  seemed  to  be  the  very  essence  of  the 
volatile  parts  of  solid  human  fseces:  and  I  learned  upon  enquiry, 
that  no  pains  had  ever  been  taken  to  separate  this  ordure  from  the 
urine,  with  which  it  was  frequently  intermixed  in  their  collections. 
To  ascertain  the  differenee  occasioned  by  this  offensive  addition,  I 
macerated  a  parcel  of  the  lichen  with  it,  in  the  usual  way,  and  ano- 
ther parcel  in  pure  aqua  ammonia,  which  1  procured  from  a  drug- 
gist; and  with  the  latter  I  produced  very  excellent  cudbear,  which, 
both  in  its  appearance  and  in  its  effects,  when  applied  to  cloth,  was 
equal  to  the  finest  sample  which  I  could  procure,  while  that  pro- 
duced with  the  impure  volatile  alkali,  before  mentioned,  was  ma- 
nifestly -very  defective,  in  the  look,  as, well  as  in  the  colour  dyed 
from  it. 


Philosophy  of  Permanent  Colours.  225 

ed  from  time  to  time,  so  as  completely  to  obviate  all 
need  of  stirring,  and  all  opportunity  for  the  escape  of 
volatile  alkali,  which  is  unavoidably  very  great,  every 
time  the  troughs,  &c.  are  uncovered  for  that  operation. 

The  colours  obtained  in  this  way,  from  the  several 
species  of  lichen,  though  possessing  great  beauty  and 
lustre  at  first,  are  so  fugacious,  even  when  dyed  upon 
wool,  that  they  ought  never  to  be  employed,  but  in  aid 
of  some  other  more  permanent  dye,  to  which  they  may 
give  body  and  vivacity;  though  some  dyers  have  been 
tempted,  by  a  love  of  gain,  to  employ  the  cudbear 
alone;  and  in  one  instance,  a  great  corporation  lately  ob- 
tained from  a  London  dyer,  the  restitution  of  several 
thousand  pounds,  as  a  compensation  for  excessive 
prices  paid  to  this  dyer  for  colours  which  ought,  and 
were  believed,  to  have  been  dyed  from  indigo  and  co- 
chineal, though  they  had,  in  fact,  been  dyed  from  cud- 
bear only. 

I  have  already  mentioned,  that  the  colour  obtained 
from  the  orchella  is  less  fugacious  and  more  beautiful 
than  that  yielded  by  any  other  species  of  lichen,  and  it 
is,  therefore,  much  more  costly.  The  application  of 
these  colours  by  dyeing  is  so  simple  and  easy,  that  no 
instruction  can  be  wanted  from  me  on  that  subject.  Its 
purple  or  violet  tint  is  the  immediate  result  of  the  union 
between  the  resinous  colouring  matter  of  the  plant,  and 
of  the  ammonia  with  which  it  is  prepared;  and  it  may 
be  made  crimson,  by  an  admixture  of,  I  believe,  any  of 
the  acids.  Alum  does  not  in  any  degree  render  the  co- 
lour more  permanent;  but  the  nitro  muriate  of  tin  is 
believed  to  produce  a  better  eiFect  in  this  respect,  though 
it  makes  the  colour  dyed  with  it,  approach  nearer  to  the 
crimson;  but  I  have  never  found  that  it  was  attended 
with  any  additional  vivacity. 

Cudbear  in  this  country  is  chiefly  employed  to  give 

VoL.I.  2  F 


226  Philosophy  of  Permanent  Colours, 

body  and  brightness  to  the  blues  dyed  with  indigo,  and 
produce  a  saving  of  that  article;  it  is  also  used  as  a 
ground  for  madder  reds,  which  commonly  incline  too 
much  to  the  yellow,  and  are  made  rosy  by  this  addition. 
It  stains  marble  durably,  as  was  first  observed  by  Dufay. 

But  though,  as  I  have  lately  mentioned,  the  purple^ 
or  violet  colour  obtained  from  these  lichens,  depends 
upon  a  combination  of  ammonia,  the  presence  of  a  cer- 
tain portion  of  oxygene  also  is  necessary  to  its  existence, 
as  I  have  already  noticed  at  p.  47,  in  regard  to  the  co- 
lour of  the  spirituous  thermometers.  Water,  coloured  by 
prepared  orchella  or  cudbear,  and  secluded  from  atmos- 
pheric air,  loses  its  purple  in  much  less  time  than  the 
spirituous  tincture;  and  I  found,  that  a  phial  being  filled 
with  it,  and  with  a  small  proportion  of  muriate  of  tin, 
recently  prepared,  and  closely  stopped,  the  purple  colour 
of  the  cudbear  completely  disappeared  in  less  than  two 
minutes,  as  I  presume,  by  an  abstraction  of  its  oxygene. 
This  is  analogous  to  the  extinction  of  the  colour  of  sul- 
phate of  indigo  by  the  same  muriate. 

Besides  the  lichens,  whose  colour  depends  upon  a 
combination  with  the  ammonia,  there  are  some  which 
afford  substantive  colours,  less  beautiful,  indeed,  but 
more  durable,  by  mere  boiling  with  water — one  of  these 
is  the  muscus  pulmonarius  of  Caspar  Bauhine,  or  the 
lichenoides  pulmonium  reticulatum  vulgare  marginibus 
peltiferis  of  Dillenius,  (p.  212)  called  Rags,  and  Stone 
Rag,  in  the  northern  parts  of  England;  which,  without 
any  mordant,  dyes  a  very  durable  dark-brown  colour 
upon  white  wool  or  cloth;  and  a  fine  lasting  black  upon 
wool  or  cloth  which  has  previously  received  a  dark  blue 
from  indigo. 

Besides  the  lichens  aiFording  substantive  colours,  there 
are  many  which,  being  employed  adjectively  with  alum, 
or  the  oxides  of  tin  and  iron,  are  capable  of  dying  yel- 


Philosophy  of  Permanent  Colours.  227 

lows,  olives,  and  a  variety  of  browns — but  they  do  not 
belong  to  this  division  of  my  subject — and  as  similar 
colours  may  be  given  at  less  expense,  with  other  means, 
I  probably  shall  not  notice  them  hereafter;  but  think  it 
sufficient  to  refer  those  who  may  wish  for  more  infor- 
mation concerning  them,  to- Hoffman's  *' Commentatio 
de  vario  Lichenum  usu,"  printed  at  Lyons,  1787. 

There  is  a  species  of  colouring  matter  diffused,  in 
greater  or  lesser  proportions,  through  the  barks  and 
other  parts  of  almost  all  trees  and  shrubs,  and  which, 
without  any  basis  or  mordant,  permanently  dyes  or 
stains  wool,  silk,  cotton,  and  linen,  of  that  particular 
kind  of  colour,  which  the  French  call  "  fauve,"  (fawn- 
colour)  and  sometimes  couleur  de  racine,  ou  de  noisette, 
(root,  or  hazel-nut  colour.)  This  being  naturally  blended 
with  some  of  the  more  valuable  colours  of  vegetables, 
frequently  does  harm,  by  degrading  or  obscuring  them. 
It  is  found  most  abundantly  in  the  peelings,  rinds,  or 
husks  of  walnuts,  (Juglans  regia),  in  the  roots  of  walnut- 
trees,  in  alder  bark,  &c.;  and  it  seems  to  acquire  both 
body  and  permanency,  by  attracting  and  combining  with 
pure  air.  M.  Berthollet  has,  however,  treated  so  fully  and 
so  well  of  the  properties  of  this  kind  of  colouring  matter, 
when  applied  substantively,  that  I  cannot  do  better  than 
refer  my  readers  to  that  part  of  his  work  which  relates 
to  it;  observing,  at  the  same  time,  that  the  colouring 
matter  in  question,  though  capable  of  being  permanently 
fixed  without  any  metallic  or  earthy  basis,  does,  in  some 
instances,  acquire  new  and  more  useful  properties,  when 
applied  with  a  basis  adjectively;  which  I  shall  notice 
hereafter,  under  the  proper  heads,  and  particularly  when 
I  come  to  treat  of  the  black  dye. 

There  are  three  species  of  poisonous  shrubs,  or  vines, 
growing  in  North  America,  and  containing  in  their  stems, 
leaves,  &c.  a  white  milky  juice,  which,  when  applied  to 


228  Philosophy  of  Permanent  Colours. 

linen,  cotton,  or  silk,  produces  a  stain,  which  soon  be- 
comes of  a  full,  strong,  and  durable  black  colour^  inca- 
pable of  being  discharged  by  repeated  washings,  or 
impaired  by  the  weather.  These  are  the  Rhus  vernix, 
(growing  likewise  in  Japan,  and  yielding  the  fine  Japan 
black  varnish);  the  Rhus  radicans;  and  the  Rhus  toxi- 
condendron,  Linn.  Some  trials,  which  I  formerly  made 
in  America,  seemed  to  indicate  the  last  of  these  as  af- 
fording the  deepest  and  most  permanent  black.  But  in 
all  of  them  this  colour  probably  depends  on  the  addition 
of  oxygene  to  the  colourable  matter;  an  addition  which, 
in  the  formation  of  indigo,  produces  only  a  blue,  whilst 
in  the  present  instance  it  changes  a  white  milky  juice  to 
the  greatest  possible  extreme,  by  rendering  it  of  a  full 
strong  black.  I  have  found  that  by  washing  the  stains 
before  the  black  was  completely  produced,  it  never  at- 
tained more  than  a  blackish  brown. 

Marking  Nut,  Or  Semecarpus  Anacardium, 
The  tree  which  Linnaeus  erroneously  denominated 
Avicennia  Tomentosa,  and  which  his  son  afterwards, 
with  more  propriety,  called  Semecarpus  Anacardium, 
produces  a  nut,  which  has  been  long  known  under  the 
name  of  Malacca  bean,  or  marking  nut,  from  the  use 
generally  made  of  it  throughout  India,  to  mark  calico 
and  silk.  The  shell  of  this  nut  is  composed  of  double 
laminae,  between  which  are  many  cells  filled  with  a  cor- 
rosive resinous  juice,  of  a  pale  milky  colour,  until  the 
nut  has  ripened,  and  then  it  becomes  a  brownish  black. 
It  is  only  soluble,  as  far  as  my  knowledge  extends,  by 
the  combined  operation  of  alcohol  and  caustic  alkali,  nei- 
ther of  which,  alone^  will  dissolve  it;  and  being  dissolved, 
it  may  be  made  to  serve  as  an  ink,  probably  of  great 
durabihty,  and  indestructible  by  any  thing  which  will 
not  also  destroy  paper.  Osbeck  says,  that  when  the  juice 


Philosophy  of  Permanent  Colours,  229 

is  employed  for  marking,  the  letters  are  commonly  co- 
vered, while  wet,  with  quick  lime,  to  obviate  the  injury 
that  might  otherwise  result  from  the  corrosive  property 
of  the  juice;  and  it  seems  that  quick  lime  is  very  gener- 
ally employed  for  this  purpose,  in  the  way  mentioned 
by  Osbeck,  or  mixed  with  the  juice  before  its  applica- 
tion. By  long  keeping,  this  juice  becomes  as  thick  as 
tar,  and  in  some  of  the  nuts  which  were  given  to  me, 
by  a  gentleman  in  whose  possession  they  had  been  for 
more  than  ten  years,  it  manifested  no  acrimony  to  the 
taste.  Some  of  it  being  topically  applied  to  while  calico, 
without  any  addition,  it  penetrated  thoroughly,  and, 
being  dried,  it  was  afterwards  boiled  with  soap,  and 
exposed  to  the  sun  and  weather,  during  two  months,  in 
which  space  the  black  colour  had  become  deeper  and 
more  decided,  as  I  presume,  by  an  absorption  of  oxy- 
gene;  but  as,  from  the  viscidity  of  the  juice,  a  redun- 
dance of  colouring  matter  had  been  applied,  the  marks 
seemed  rather  to  have  been  painted  than  stained  or 
dyed. 

Dr.  Roxburgh  says,  these  nuts  are  employed  by  the 
Telinga  physicians,  to  cure  the  venereal  disease.  They 
are  also  pickled  like  olives,  whilst  very  young,  and, 
Avhen  nearly  ripe,  are  applied  as  a  mild  caustic  to  sores, 
&c.  Lamarck,  and  the  French  botanists,  have  restored 
to  this  tree,  the  name  of  anacardium^  by  which  it  was 
first  distinguished,  from  the  resemblance  of  its  nut  to 
the  shape  of  a  heart  (somewhat  flattened);  and  taking 
away  this  name  from  the  Cashew  tree,  to  which  it  ought 
never  to  have  been  applied,  (as  its  nuts  are  kidney  shap- 
ed,) they  have  denominated  the  latter  cassuvium  po- 
miferum,  which  is  the  name  formerly  given  to  it  by 
Rhumphius. 

Being  at  Barbadoes  in  the  year  1805,  a  parcel  of  these 
nuts  was  given  to  me  by  Mr.  Simmonds,  a  very  pro- 


230  Philosophy  of  Permanent  Colour ji* 

mising  young  botanist,  (then  in  the  family  of  the  go- 
vernor Lord  Seaforth,)  who  was  prematurely  stopped 
in  his  pursuit  of  knowledge,  soon  after,  by  death,  at 
Surinam.  These  nuts  had  been  recently  gathered,  hav- 
ing grown  on  a  tree  in  the  garden  of  the  government 
house,  (pilgrims,)  but  were  necessarily  abortive,  there 
being  no  male  tree  on  the  island.  Their  juice  I  found 
sufficiently  fluid,  though  only  of  a  dark-brown  colour, 
when  spread  either  on  calico  or  paper,  but  it  afterwards' 
became  black,  by  exposure  to  atmospheric  air.  Strong 
nitric  acid  changed  it  to  an  orange;  but  oil  of  vitriol  did 
not  alter,  though  it  weakened  the  colour,  and  this  was 
the  case  when  muriatic  acid  was  applied  to  it.  Muriate 
of  tin  produced  no  sensible  effect  upon  it.  This  juice 
was  a  little  acrid  to  the  taste. 

There  are  a  considerable  number  of  other  vegetables, 
whose  juices  by  simple  topical  application  permanently 
stain  linen  or  cotton,  and  the  stains,  by  exposure  to  the 
atmosphere,  generally  become  black,  or  nearly  so.  One 
of  these  is  the  amyris  toxifera,  or  poison  ash,  which 
Catesby  (vol.  2,  p.  43,)  has  described  as  a  "toxicoden- 
dron foliis  alatis  fructu  purpureo,"  &c.  adding,  that 
"  from  the  trunk  of  this  tree  distils  a  liquid  black  as 
ink,  which  the  inhabitants  say  is  poison."  *' It  grows 
usually  on  rocks  in  Providence,  Ilathera,  and  other  Ba- 
hama islands.  It  is  also  found  in  South  Carolina  and 
Georgia." 

The  camocladia  integrifolia,  called  Burnwood,  or 
Papau  wood,  and  by  some  Maiden  plumb,  in  Jamaica, 
abounds  in  a  moderately  glutinous  sap,  which,  as  Jac- 
quin  asserts,  will  grow  black  by  exposure  to  atmos- 
pheric air,  and  stain  the  hands  of  a  deep  black  colour, 
only  to  be  removed,  with  great  difficulty,  by  washing 
with  soap. 


Philosophy  of  Permanent  Colours,  231 

Another  species  of  this  genus,  the  camocladia  den- 
tata,  growing  in  South  America  and  in  Cuba,  emits, 
when  wounded,  a  viscid  milky  juice,  smelling  like  hu- 
man excrement,  which,  by  exposure  to  the  air,  becomes 
black,  and  gives  durable  stains  to  linen,  &c.  as  well  as 
to  the  fingers.  It  is  mentioned  by  Ulloa  under  the  name 
of  guao. 

Another  species  of  this  genus,  Camocladia  punctuata, 
or  dotted  stalked  Eclipta,  grows  in  the  West  Indies,  and 
contains  a  thin  greenish  sap,  which  turns  black  by  ex- 
posure to  the  air,  and  may  be  used  as  ink.  Jacquin  says, 
the  negroes  sometimes  endeavour  to  increase  the  black- 
ness of  their  skins  by  washing  with  this  juice. 

The  Eclipta  erecta  (cotula  alba,  Linn.)  affords  a  juice 
which  the  inhabitants  of  Cochin  China,  as  Loureiro  as- 
serts, (p.  505,)  employ  to  dye  human  and  other  hairs 
permanently  black,  and,  therefore,  call  it  ink  plant; 
"  herba  atramenti." 

Several  species  of  the  genus  Rauwolfia  abound  in  a 
glutinous  milky  juice,  which  blackens  by  exposure  to 
the  air,  and  gives  lasting  dark-coloured  stains;  one  of 
these,  R.  canescens,  ('*  le  bois  laiteux  febrifuge,"  of 
Pouppee  des  Fortes,)  bears  juicy  black  berries,  which, 
at  maturity,  may  be  used  as  ink,  without  any  prepa- 
ration, and  are  said  to  give  a  lasting  black  stain  to 
iinen. 

The  hippomane  mancinella,  or  manchineel  tree,  con- 
tains a  very  acrid  juice  or  sap,  which,  if  in  cutting  the 
tree,  or  otherwise,  it  falls  on  linen,  soon  produces  a 
black  stain,  which  afterwards  becomes  a  hole,  from  the 
caustic  quality  of  the  sap:  probably  lime  would  correct 
this,  as  it  does  that  of  the  juice  of  the  marking  nuts. 

The  terminalia  vernix  of  Lamarck,  (Tsi-Chu  of  the 
Chinese,)  contains,  in  every  part  of  it,  a  caustic  milky 


232  Philosophy  of  Permanent  Colours • 

juice,  which,  exuding  from  the  tree  when  wounded, 
thickens  and  becomes  black  like  pitch,  by  being  in 
contact  with  the  air,  and  is  used  by  the  Chinese  as  a 
varnish  for  furniture. 

I  could  mention  several  other  vegetables  with  similar 
properties,  but  believe  it  to  be  unnecessary. 


Philosophy  of  Permanent  Colours.  233 

CHAPTER  VI. 
Of  Mineral  Substantive  Colours. 

"  Rien  n*est  plus  facile  dans  les  sciences  fondet-s  sur  I'exp^rience  que  de  muUi> 
"  plier  les  fails  particuliers;  mais  ces  faits  ne  sont  dignes  d'attention,  que  lorsqu'ils 
"serventk  conduire  a  des  v^rites  gj^neiales,  ou  que  pr^sentant,  au  contraire,  des 
**  singularit^s  nouvelles  et  irapr^vues,  ils  deviennent  un  objet  de  recherches."  Hist. 
de  I'ACAD.  Re,  &c.  1777. 

Each  of  the  metals  and  semi-metals  is  capable,  when 
dissolved,  of  becoming  a  basis  or  mordant,  for  fixing 
and  modifying  some  at  least  of  the  different  adjective 
animal  or  vegetable  colouring  matters,  with  more  or 
less  advantage,  by  dyeing.  But  besides  this  property, 
which  will  be  made  a  subject  of  future  consideration, 
several  metals  and  semi-metals  afford  coloured  solu- 
tions or  oxides,  which  are  capable  of  being  united  and 
fixed  directly  in  the  fibres  of  linen,  cotton,  silk,  or  wool, 
and  of  thereby  producing  various  permanent  substan- 
tive colours.  It  is  indeed  true,  that  hitherto  but  few  me- 
tallic preparations,  excepting  those  of  iron  and  copper, 
have  been  used  in  this  way,  or  for  this  purpose;  I  mean 
that  of  giving  substantive  colours. 

Iron. 
This,   by  whatever  means  dissolved,  possesses  so 
much  affinity  to  linen  and  cotton,*  that  when  applied  to 
them,  its  oxide  or  calx  decomposes  and  fixes  itself  per- 
manently irfTtieir  fibres,  and  thereby  produces  colours, 

*  The  affinity  between  cotton  and  the  oxide  of  iron  is  so  strong, 
that  by  simply  moving  the  former  about  in  water,  wherein  the  sul- 
phate of  iron  has  been  dissolved,  and  left  exposed  to  atmospheric 
air  for  a  few  days,  it  will  gradually  attract  and  take  to  itself  every 
particle  of  the  metallic  oxide. 

Vol.  I.  2Cx 


234  Philosophy  of  Permanent  Colours, 

differing  considerably  from  each  other,  according  to  tiic 
different  states  in  which  the  oxide  may  have  been  ap- 
plied, particularly  in  respect  of  the  portion  of  oxygene 
combined  with  it.  But  as  the  oxide  of  iron,  m  all  stateSy 
and  however  obtained,  is  disposed  to  attract  the  oxy- 
gene of  the  atmosphere,  its  different  colours,  by  this  ad- 
dition, soon  lose  their  peculiar  shades  or  variations,  and 
acquire  the  rusty  colour  commonly  called  iron-mould. 
This  addition,  moreover,  soon  renders  the  oxide  in 
some  degree  corrosive,  and  joined  perhaps  to  the  rigi- 
dity which  it  occasions  by  a  sort  of  concretion  in  the 
fibres  of  wool,  silk,  cotton,  and  linen,  it  disposes  them 
to  become  brittle,  or  less  durable.  There  are  few,  if 
any,  who  have  not  observed  instances  of  this  effect 
from  spots  of  what  is  called  iron-mould  on  linens,  &c. 
which  produce  holes,  long  before  any  occur  in  other 
places.  But  where  iron  is  used  in  dyeing,  merely  as  the 
basis  of  animal  or  vegetable  colouring  matters,  these 
last,  by  combining  with  its  particles,  lessen  their  dis- 
position to  attract  oxygene,  and  by  keeping  them  far- 
ther asunder,  so  far  prevent  their  concretion,  as  in  a 
considerable  degree  to  obviate  the  rottenness  in  ques- 
tion; though  there  is  but  too  much  reason  to  fear,  that 
even  in  this  way,  stuffs  dyed  with  a  ferruginous  basis  or 
mordant,  are  less  durable  from  that  circumstance;  and 
it  probably  is  from  the  use  of  this  metal,  that  the  rot- 
tenness so  generally  complained  of,  as  accompanying 
the  black  dye,  principally  results. 

But  in  this  place  I  am  only  to  notice  the  use  of  iron, 
as  affording  substantive  colours;  and  for  these,  its  use 
is  confined  to  linens  and  cottons,  to  which  its  oxide  is 
very  frequently  applied,  topically,  in  calico  printing,  to 
produce  partial  buff,  or  rusty  yellow,  stains  or  figures, 
and,  in  general  dyeing,  to  produce  imitations  of  the 
nankin  brown,  as  well  as  a  considerable  variety  of  buff 


Philosophy  of  Permanent  Colours.  235 

colours;  for  all  which  purposes,  the  solutions  of  iron  by 
vegetable  acids  are  preferred,  as  being  least  corrosive, 
and  therefore  least  hurtful  to  the  fibres  of  linen  and 
cotton. 

Among  the  vegetable  acids,  that  of  vinegar,  or  alegar, 
was  for  a  long  time  almost  exclusively  employed  to  dis- 
solve iron,  and  make  that  preparation  which  has  been 
commonly  denominated  iron  liquor  (acetite  of  iron). 
But,  within  a  few  years,  another  acid  has  been  very  fre- 
quently substituted  for  the  former;  viz.  the  pyroligneous, 
distilled  from  wood.  M.  Chaptal  justly  considers  this  as 
being  truly  an  acetic  acid,  in  combinatton  with  a  portion 
of  empyreumatic  oil,  which,  instead  of  diminishing,  in- 
creases its  utility  for  most  of  the  purposes  of  dyeing, 
and  especially  for  that  of  dissolving  iron;-*  and  when  so 
dissolved,  its  oxide  may  be  obtained  at  different  degrees 
of  oxidation,  but  its  union  w^ith  the  fibres  of  linen  and 
cotton,  and  the  colours  thence  resulting,  are  most  per- 
manent when  the  oxidation  is  greatest.  M.  Chaptal  has 
however  discovered,  that  the  various  buff,  and  the  imi- 
tations of  nankin  colours,  may  be  greatly  improved  by 

*  «  Cet  acide,"  says  M.  Chaptal,  *'  est  prefere  au  vinaigre  pour 
tons  les  usages  de  la  teinture  et  de  rimpression  sur  toile:  il  porte 
avec  lui  une  huile  qui  forme  un  excellent  mordant  pour  les  toiles 
de  lin  et  de  colon,  et  deja  il  remplace  Tacide  acetique  dans  les  tein- 
tures,  oil  il  sert  a  composer  ce  qu'oo  appelle  le  bouillon  noir,  ou  le 
mordant  pour  les  noirs,  les  violets,  les  pruncaux,  les  lilas,  les  nan- 
kins, etc.  Les  couleurs  portees  sur  ce  mordant  sont  plus  nourries, 
plus  vivesj  et  beaucoup  plus  fixes,  que  celles  que  produit  Tacetate 
ordinaire  de  fer."  Chim.  appliquee  aux  Arts,  tom.  iii.  p.  169.  He 
adds,  in  the  next  page,  "  Lorsqu*on  veut  employer  aux  usages  de 
la  teinture  I'acide  acetique  provenant  de  la  distillation,  il  est  inutile, 
il  seroit  raeme  prejudiciable  a  ses  proprietes,  de  lui  enlever  Thuile 
qu'il  tient  en  dissolution." 

The  pyroligneous  acid  is  dark-coloured,  and  exhales  an  empy- 
reumatic odour. 


236  Philosophy  of  Permanent  Colours, 

combining  the  oxide  of  iron  with  alumine^  or  the  earth 
of  alum;  and  for  this  purpose  he  first  impregnates  the 
cotton  with  the  oxide  of  iron,  by  working  it  sufficiently 
and  equally  in  a  solution  of  that  metal  by  the  pyrolig- 
neous,  or  other  vegetable  acids,  or,  in  default  of  these, 
in  a  solution  of  the  sulphate  of  iron,  marking  three  de- 
grees on  the  areometre  of  Beaume,  and,  after  wringing 
it  properly,  plunges  the  cotton  immediately  into  a  solu- 
lution  of  potash  marking  two  degrees,  with  which  a  sa- 
turated  solution  of  alum  has  been  just  mixed,  but  so  as 
notXo  precipitate  thealumine.  By  this  last  mixture,  the 
colour  of  the  oxide  of  iron  is  considerably  raised,  and 
it  also  acquires  an  agreeable,  smooth,  even,  and  soft  ap- 
pearance like  velvet,  which  could  never  be  produced 
with  the  oxide  of  iron  unmixed;  it  has  moreover  the 
advantage  of  preserving  the  fibres  of  cotton  from  injury 
by  the  solution  of  iron:  after  being  thus  immersed  five 
or  six  hours,  the  cotton  is  to  be  properly  wrung,  washed, 
and  dried;  and  by  the  last  part  of  this  operation,  it  will 
generally  become  deeper,  from  an  accession  of  oxy- 
gene.  M.  Chaptal  distinguishes  the  varieties  of  colour 
dyed  in  this  way,  by  the  names  of  "  nankin,  chamois, 
noisette,  et  rouille."  Ann.  de  Chim.  tom.  26.  p.  270. 

The  application  of  potash  conjointly  with  an  oxide  of 
iron,  but  without  alum,  for  dyeing  the  colours  before 
mentioned,  has  been  practised,  particularly  at  Man- 
chester, for  almost  half  a  century.  But  for  this  purpose 
a  solution  of  iron  by  aquafortis  was  commonly  employ- 
ed, though  injudiciously,  as  it  certainly  contributed 
more  than  any  other,  to  hurt  the  fibres  of  the  linen  or 
cotton  dyed  therewith.*  All  these  colours,  though  in 

^'  *  In  the  Transactions  of  the  Dublin  Society,  vol.  i.  part  1,  may- 
be found  an  account  of  "  a  process  for  dyeing  a  nankin  colour,"  by 
Mr.  Richard  Brewer.  The  colour  is  produced  by  an  oxide  of  iron; 


Philosophy  of  Permanent  Colours,  237 

other  respects  very  durable,  are  liable  to  be  spotted, 
and  made  black  by  being  accidentally  wetted  with  a 
little  tea,  or  with  the  juices,  or  infusions  of  a  great 
number  of  vegetable,  and  some  animal  matters,  which 
are  capable  (as  will  be  hereafter  noticed)  of  producing 
an  ink  with  iron. 

For  topical  application  by  the  pencil,  or  block,  Hauss- 
man  recommends  Stahi's  alkaline  tincture  of  iron,  made 
by  dissolving  that  metal  in  aquafortis,  and  adding  to  it 
carbonate  of  potash  in  excess^  sufficient  to  decompose 
and  re-dissolve  the  nitrous  oxide  of  iron;  and  afterwards 
thickening  the  solution  with  gum,  &c.  as  usual.  Com- 
monly, however,  a  solution  of  iron  by  some  of  the  vege- 
table acids  (called  iron  liquor)  is  employed  for  this  pur- 
pose, adding  to  it  a  portion  of  sulphate  of  iron,  to 
increase  its  strength,  when  very  full  and  deep  stains  arc 
required. 

Iron  dissolved  by  muriatic  acid,  assumes  a  greenish 
colour,  and  the  solution  being  applied  to  linen  or  cotton, 
the  oxide  adheres  permanently;  and,  by  an  accession  of 
oxygene,  affords  a  fine  yellow  stain.  A  single  washing 
will  however  so  far  affect  the  proportions  on  which  this 
colour  depends  as  to  reduce  it  to  the  common  iron- 
mould  colour. 

Copper. 
Only  two  oxides,  or  compounds  of  this  metal  with 
oxygene,  are  known  to  exist;  one  of  these,  naturally 
formed,  is  distinguished  by  the  name  of  ruby  copper 
ore.  Its  colour  is  a  dark  or  brownish  red;  though  the 
artificial  imitations  of  it  have,  I  believe,  never  risen 
much  above  an  orange  colour.   This  native  oxide  is 

and  the  process  consists  of  eight  troublesonne  and  expensive  opera- 
tions, which  do  not  seem  to  be  compensated  by  any  adequate  ad- 
vantage. 


238  Philosophij  of  Permanent  Colours. 

supposed  to  contain  about  eleven  per  cent,  of  oxygene; 
but  neither  it,  nor  any  artificial  imitation  of  it,  has  yet, 
as  I  believe,  been  employed  for  a  substantive  colour  in 
dyeing  or  calico  printing.  I,  however,  very  recently  and 
unexpectedly  produced,  and  Jixed  permanently  upon 
calico,  a  brownish  red  oxide  of  copper,  very  nearly  re- 
sembling the  ruby  copper  ore  in  colour.  It  has  with- 
stood repeated  washings  with  soap,  and  six  weeks  ex- 
posure to  the  weather,  without  alteration;  and  may,  I 
think,  prove  useful,  by  simple  topical  application,  in 
calico  printing;  but  in  this  instance,  it  was  the  result  of 
a  complicated  mixture,  made  for  another  purpose,  and 
I  have  not  yet  had  time  to  simplify  the  process  suffi- 
ciently. When  I  shall  have  done  so,  I  intend  to  make 
it  public.  In  appearance  it  resembles  another  very  per- 
manent colour,  which  I  discovered  twenty  years  ago.  I 
mean  the  red  prussiate  of  copper,  to  be  mentioned  here- 
after. 

The  other  oxide  of  copper  is  supposed  to  contain 
about  twenty  per  cent,  of  oxygene;  but  it  has  never, 
I  believe,  been  employed  for  dyeing  or  calico  printing. 

The  green  colour  exhibited  by  most  of  the  prepara- 
tions of  copper,  commonly  results  from  the  absorption, 
or  addition  ,of  carbonic  acid,  for  which  the  oxides  of 
copper  have  a  marked  affinity;  it  may  be  produced  also 
by  the  admixture  of  muriatic  and  some  other  acids. 
There  is  however,  I  believe,  none  of  the  acid  green 
solutions  of  copper  or  its  oxides,  which  after  being  ap- 
plied simply  to  cotton  or  linen  will  bear  to  be  washed 
with  soap,  though  their  colours  generally  withstand  the 
impressions  of  sun  and  air  for  a  considerable  time.  But 
if  liquid  ammonia  be  saturated  with  copper,  and  thick- 
ened with  gum,  it  may,  by  simple  topical  application, 
be  fixed  upon  linen  or  cotton,  where,  by  an  evaporation 
of  a  part  at  least  of  the  volatile  alkali,  and  an  absorption, 


Philosophy  of  Permanent  Colours  •  239 

probably,  of  both  oxygene  and  carbonic  acid,  its  blue 
colour  will  be  changed  to  a  green  resembling  that  of 
verdigrisCy  or  rather  that  of  the  malachite,  which  will 
very  sufficiently  resist  the  impressions  of  sun  and  air, 
and  bear  a  considerable  number  of  washings  with  soap 
without  being  much  weakened  thereby.  It  may,  there- 
fore, be  usefully  employed  in  this  way,  especially  upon 
Jine  muslins,  by  reason  of  the  great  delicacy  of  its  co- 
lour, and  the  facility  of  its  application.  I  have  several 
times  thought  that  an  effect  somewhat  better  had  result- 
ed, when,  instead  of  dissolving  the  copper  by  ammonia, 
I  combined  the  latter  with  a  nitrate  of  that  metal.  Ver- 
digrise  dissolved  by  ammonia,  also  produces  good  ef- 
fects used  in  this  manner.  A  similar  beautiful,  though 
pale  green,  may  be  substantively  dyed  upon  woollen 
cloth,  by  the  sulphate  of  copper  with  a  sufficient  por- 
tion of  carbonate  of  lime,  to  neutralize  the  acid.  This 
colour  will  not  indeed  bear  the  action  of  soap,  but  it 
does  not  appear  to  suffer  any  considerable  change  or 
diminution,  by  the  impressions  of  sun  and  air  for  a  long 
time. 

The  oxides  and  solutions  of  copper  are  all  suscepti- 
ble of  combination  with  most  of  the  adjective  colouring 
matters,  and  may  be  usefully  employed  as  mordants  or 
bases  with  some  of  them,  which  will  be  duly  noticed 
hereafter. 

Gold. 
When  this  metal  is  dissolved  in  nitro-muriatic  acid, 
the  result,  as  Proust  has  observed,  seems  to  be  a  pure 
and  simple  muriate  of  gold:  and  when  beaten  into  leaves, 
and  burnt  by  electricity,  or  calcined  by  the  sun's  rays, 
concentrated  and  reflected  by  a  burning  mirror,  it  affords 
z.  purple  oxide:  and  this  it  also  does  when  precipitated 
from  aqua-regia  by  the  muriate  of  tin.  In  this  last  opera- 


240  Philosophy  of  Permanent  Colours* 

lion,  as  well  as  in  the  former,  the  purple  colour  depends 
entirely  upon  the  oxide  of  gold;  that  of  tin,  though 
combined  with  it,  being  colourless.  This  precipitate  has 
been  called  the  purple  of  Cassius,  though  improperly, 
because  it  was  known  to  earlier  chemists,  particularly 
Neri,  Glauber,  and  Kunkel.  The  supposed  oxides,  or 
precipitates  of  gold,  obtained  by  mixing  either  of  the 
alkalies,  or  lime  or  magnesia  with  a  solution  of  gold, 
are  yellow;  but  such  precipitates  appear  (as  Davy  has 
observed)  to  be  triple  compounds.  Having  soaked 
muslin  in  a  diluted  solution  of  gold  by  aqua  regfia,  for 
a  single  minute,  I  exposed  it  whilst  wet  to  the  direct 
rays  of  the  sun  in  the  month  of  September,  and  found, 
in  less  than  a  quarter  of  an  hour,  that  the  fine  yellow 
colour  which  it  had  received  from  the  muriate  of  gold, 
was  become  partially  violet,  excepting  only  a  few  round 
spots,  to  which  I  had  previously  applied  a  solution  of 
crystals  of  soda  thickened  with  gum;  in  these  spots  the 
alkali  had  neutralized  the  acid,  and  produced  a  colour 
resembling  that  of  bright  iron-mould,  upon  which  the 
rays  of  the  sun  made  no  impression,  or  change;  the 
violet  colour,  so  produced,  soon  became  general,  ex- 
cepting the  spots  last  mentioned;  and,  by  a  further  ex- 
posure to  the  sun's  rays,  this  colour  was  gradually  red- 
dened, and  converted  to  a  sort  of  crimson  purple,  in 
consequence,  as  I  presume,  of  a  farther  de- oxygenation 
of  the  metal,  which,  from  this  progressive  change  of 
colour,  appears  to  be  susceptible  of  different  degrees  of 
oxidizement.  A  similar  change  was  produced,  much 
more  expeditiously,  when  I  applied  a  recently-prepared 
muriate  of  tin  to  cotton,  impregnated  with  a  solution  of 
gold  in  aqua-regia,  and  dried  in  the  dark;  an  abstraction 
of  oxygene,  and  a  partial  revival  of  the  gold,  having 
been  almost  instantaneously  manifested,  by  the  appear- 
ance of  a  viol"-  ur,  where  the  muriate  of  tin  had 


Philosophy  of  Permanent  Colours.  241 

been  applied,  and  in  no  other  part.  Count  Rumford, 
also,  (as  is  stated  in  the  Phil.  Trans,  for  1798,)  produc- 
ed a  purple  colour  by  impregnating  white  silk,  linen, 
and  cotton,  with  a  solution  of  gold,  and  exposing  them 
to  the  direct  rays  of  the  sun,  but  he  had  previously 
separated  a  great  part  of  the  nitro-muriatic  acid,  employ- 
ed to  dissolve  the  gold,  by  evaporating  the  solution  to 
dryness,  and  afterwards  re-dissolving  the  oxide,  or  salt 
of  gold,  in  water;  a  precaution  which  I  did  not  employ. 
He  found,  (as  I  have  done)  that  no  change  of  colour 
took  place  in  the  dark;  but  here  it  must  be  observed,  that 
he  made  no  trial  of  the  deoxygenating  power  of  the 
muriate  of  tin,  which,  when  employed  by  me,  readily 
produced  the  violet  colour  without  the  aid  of  light.* 

Antecedently,  however,  to  count  Rumford's  experi- 
ments, Mrs.  Fulhame  (in  an  essay  on  combustion,  pub- 
lished in  1794)  had  given  an  account  of  several  ingeni- 
ous attempts  not  only  to  fix  the  oxides  of  gold  upon 
silk,  but  to  revive  the  gold  afterwards  with  its  metallic 
lustre,  principally  by  the  application  of  hydrogene  gas, 
and  phosphuretted  hydrogene,  which  in  some  degree 
produced  the  desired  effect,  though  it  was  found  impos- 
sible to  make  the  revivification  so  generally  equal,  as  to 
produce  that  uniformity  of  gilding,  which  could  alone 
compensate  the  expense  of  it. 

*  More  than  half  a  century  ago,  Hellot  had  observed  that  charac- 
ters traced  on  writing-paper  with  a  diluted  nitro-muriate  of  gold 
began,  after  a  few  hours  exposure  to  the  air,  (he  should  have  said 
lij^/iti)  to  manifest  colour,  and  soon  after  became  of  a  very  dark 
violet — "violet  fence  prcsque  noir."  But  when  shut  up  in  a  close 
box,  he  says,  the  writing  did  not  become  visible  during  several 
months.  And  he  adds,  that  the  like  happened  to  characters  written 
with  a  diluted  nitrate  of  silver,  though  they  became  very  visible  in 
in  the  space  of  hour  when  exposed  to  the  sun's  rays.  See  Mem.  de 
i'Acad.  R.  &c.  1737. 

Vol.  I.  2  H 


242  Philosophy  of  Permanent  Colours. 

In  consequence  of  Mrs.  Fulhame's  publication,  count 
Rumford  attempted  a  more  complete  revival  of  gold,  by 
mixing  with  his  aqueous  solution  of  its  salt  (before 
mentioned)  sulphuric  ether,  which  soon  attracted  and 
united  itself  with  the  gold,  swimming  upon  the  surface 
and  leaving  the  water  colourless:  and  this  mixture  being 
afterwards  exposed  to  the  rays  of  the  sun,  the  metal 
soon  revived  in  the  form  of  gold  leaf. 

Such  a  mixture  of  sulphuric  ether  and  the  salt  of  gold 
has  lately  been  found  useful  to  gild  the  points  of  lancets^ 
and  protect  them  from  rust;  and  if  the  expense  be  not 
too  great,  I  am  persuaded  that  white  silks  might  be  pre- 
manently  gilt  wdth  it,  in  spots  or  figures,  for  which  a 
perfect  equality  in  the  metallic  appearance  of  the  gold 
would  not  be  required. 

That  precipitate  of  gold  by  tin,  which  has  been  com- 
monly called  the  purple  of  Cassius,  was  soon  after  its 
discovery  combined  with  glass  to  imitate  Rubies^  which 
it  did  perfectly,  at  least  in  their  appearance,  though  not 
in  their  hardness;  and  in  later  times,  this  precipitate  has 
been  generally  employed  as  a  finer  sort  of  enamel  for 
porcelain,  &c.  By  varying  the  proportions  of  tin,  or 
rather  of  its  solution,  the  colours  of  this  precipitate  may 
be  varied  through  all  the  intervening  shades  from  violet 
to  crimson;  and  the  precipitate,  with  all  its  various  co- 
lours, may  be  permanently  fixed  as  a  stain  or  dye  upon 
silk,  linen,  or  cotton,  by  applying  to  them,  either  the 
solution  of  tin  first,  and  afterwards  the  solution  of  gold; 
or  the  solution  of  gold  first,  and  afterwards  that  of  the 
tin:  it  will  be  advantageous,  however,  to  let  the  silk,  &c. 
to  which  one  solution  has  been  applied,  become  dry  be- 
fore the  second  is  superadded. 

Lately  Haussma^n  has  found  means  to  produce  a  pur- 
ple mixture  of  tin  and  gold,  without  any  precipitation ^ 


Philosophy  of  Permanent  Colours.  243 

by  dissolving  the  metals  with  a  great  excess  of  the  acids; 
which  excess  retains  the  oxides,  suspended  in  the  water, 
notwithstanding  their  union,  and  such  a  partial  deoxy- 
genation  of  the  gold,  as  is  necessary  to  its  violet  colour. 

In  this  purple  liquor  diluted,  silk  may,  as  he  says,  be 
made  to  receive  the  most  durable  colours,  by  repeated 
immersions^  &c.  which  are,  as  I  presume,  necessary,  by 
reason  of  the  redundant  acidity  of  the  liquor.  I  do  not, 
however,  think  that  any  benefit  can  result  from  thus  ap- 
plying the  solutions  of  these  metals  mixed,  and  at  the 
same  times,  rather  than  separately;  for  in  the  latter  way 
two  immersions  will  be  sufficient:  and  it  is  to  be  feared 
that  this  purple  from  gold,  notwithstanding  its  great 
beauty  and  durability,  will  prove  too  costly  for  any  thing, 
but  a  partial  application  in  spots  and  figures. 

In  my  judgment  the  principal,  if  not  sole  use  of  the 
solution  of  tin,  in  producing  this  purple,  is  that  of  ab- 
stracting oxygene  from  the  gold;  an  effect  which  may 
be  produced  by  other  means.  I  have  repeatedly  found, 
that  when  a  solution  of  gold  in  aqua-regia  was  applied 
to,  and  suffered  to  remain  upon  my  fingers,  they  receive 
a  purple  stain  which  nothing  could  remove,  but  an  abra- 
sion or  wearing  off  of  the  skin;  and  I  have  produced  a 
similar  effect  from  a  solution  of  gold  applied  to  silk, 
cotton,  and  linen,  previously  impregnated  with  matters 
suited  (in  like  manner)  to  abstract  oxygene;  such  as  ani- 
mal glue,  linseed  oil,  caustic  alkalies,  yolks  and  whites 
of  eggs  beat  up  with  sugar,  or  with  orpiment,  alkaline 
sulphurets,  &c.  &c.;  and,  cseteris  paribus,  I  have  found 
that  the  more  the  oxide  of  gold  was  deprived  of  oxygene, 
the  more  its  colour  approached  to  the  crimson. 


244  Philosophy  of  Permanent  Colours. 

Silver. 

The  colours  to  be  ob.tained  substantively  from  the 
metals,  excepting  those  of  iron  and  copper,  chiefly  de- 
pend upon  a  partial  revival  of  the  metal;  w^hich  revival 
cannot  take  place,  without  its  abstraction  or  separation 
from  the  acid  by  which  it  has  been  dissolved;  and  to 
promote  this  abstraction,  it  is  convenient  and  sometimes 
necessary  to  impregnate  the  linen  or  cotton  intended  to 
be  dyed  or  stained,  with  some  of  the  animal,  alkaline, 
and  deoxygenating  substances  just  mentioned,  as  con- 
tributing to  precipitate  and  partly  revive  the  oxide  of 
gold. 

This  observation  is  particularly  applicable  to  the  ox- 
ide of  silver,  which  is  properly  of  an  olive-brown  colour, 
but  is  rendered  almost  black  by  being  deprived  of  a 
part  of  its  oxygene,  and  thereby  in  some  degree  resto- 
red to  its  metallic  form.  The  powerful  efficiency  of  the 
sun's  rays  in  the  deoxygenation  of  silver  has  been  al- 
ready noticed  at  p.  40. 

Leuwenhoek  mentions  (Philosoph.  Transactions,  vol. 
xxiv.),  that  by  touching  nitrate  of  silver,  his  fingers 
were  stained  black;  and  that,  finding  it  impossible  other- 
wise to  remove  the  stain,  he  cut  off"  and  burnt  the 
skin,  and  then  examining  it  by  a  microscope,  he  found 
the  silver  revived  in  a  multitude  of  little  globules. — "  I 
**  have  lying  on  my  desk  (continues  he),  a  linen  hand- 
"  kerchief,  which  was  stained  with  aqua-fortis,  impreg- 
"  nated  with  silver,  with  a  large  black  spot  about  as 
"  large  as  a  shilling;"  and  he  adds,  that  having  ineffec- 
tually tried  to  discharge  the  colour  by  six  washings,  and 
by  laying  the  handkerchief  out  to  bleach,  he  cut  out  the 
stained  part,  burnt  it  to  coal,  and  viewing  it  by  a  micro- 
scope, saw  thousands  of  fine  silver  globules  therein.  The 
effect  here  mentioned  to  have  been  produced  upon  the 


Philosophy  of  Permanent  Colours,  245 

skin,  accords  with  that  which   sohitions  of  silver  are 
known  to  produce  in  blackening  hair,  and  other  animal 
substances;  but  in  reading  this  account,  I  thought  it  ex- 
traordinary that  clean  linen,  impregnated  with  no  animal, 
inflammable,  or  alkaline  matter,  should  so  far  deprive 
nitrate  of  silver  of  its  acid,  as  to  produce  the  effect  des- 
cribed;  and   I  repeated  the  experiment  several  times 
without  success.  At  length,  however,  I  took  a  silver 
tea-spoon,  which  had  stood  half  filled  with  aqua-fortis 
for  several  weeks,  and  which  on  the  hollow  inside  was 
become  almost  black  by  it,  and  by  the  oxygene  of  at- 
mosphere which  it  had  attracted,  and  having  poured  out 
the  more  fluid  part  of  the  solution,  I  rubbed  a  bit  of 
cambric  against  the  wet  oxidated  hollow  surface,  and 
hanging  it  up  for  a  few  days  in  the  open  air,  on  the  south 
side  of  a  wall,  I  found  the  cambric  permanently  stained  of 
a  very  dark  violet  colour.  A  fine  piece  of  cotton,  however, 
by  the  same  means  received  only  a  very  slight  discolo- 
ration. But  cotton,  when  impregnated  with  soda  and  the 
acidulous  arseniate  of  potash,  acquired  a  strong  durable 
slate  colour  by  being  touched  with  diluted  nitrate  of 
silver;  a  drab  colour  by  the  same  means,  when  impreg- 
nated with  soda  and  sugar;  a  dark  olive  brown,  with 
sulphuret  of  potash  (liver  of  sulphur),  and  spirit  of  wine; 
and  the  like  with  soda,  liver  of  sulphur,  and  sugar;  and 
being  impregnated  with  white  of  ^gg^  beat  up  in  water 
with  sugar,  the  cotton  received  from  the  nitrate  of  silver 
a  very  strong  brownish  black;  and  when  caustic  vege- 
table alkali  was  added,  it  became  a  little  blacker.  The 
yolk,  instead  of  the  white  of  q^%,  produced  nearly  the 
same  effect.  All  these  colours  were  often  washed,  and 
exposed  for  a  long  time  to  the  weather,  without  being 
changed.* 

*  During  the  last  twenty  years  an  ink  has  been  sold,  and  exten- 
sively used  for  marking  linen,  &c.  which  it  does  permanently^  by 


246  Fhilosophy  of  Permanent  Colours, 

Mercury, 
The  oxides  of  mercury  very  easily  give  up  their  oxy- 
gene,  and  are,  therefore,  readily  precipitated  by  the 
means  before  mentioned,  upon  vegetable  as  well  as  ani- 
mal substances,  affording  generally  either  black  or  dark 
colours,  though  of  but  little  permanency,  because  the 
residue  of  their  oxygene  soon  separates,  and  the  mercury 
recovers  its  fluid  metallic  form.  Nitrate  of  mercury  ap- 
plied to  cotton,  vidiich  had  been  impregnated  with  soda, 
produced  at  first  a  yellow,  which  soon  changed  to  an 
olive,  and  being  washed  with  soap,  to  a  full  black  colour; 
but  after  a  few  days  exposure  in  the  open  air,  it  almost 
entirely  disappeared.  On  cotton,  impregnated  with  soda 
and  sulphuret  of  potash,  it  immediately  produced  a 
black,  which,  by  washing  and  exposure  in  open  air, 
changed  in  about  ten  days  to  an  olive,  and  soon  after 
disappeared.  On  cotton,  impregnated  with  sulphuret  of 

means  similar  to  those  just  mentioned.  To  prepare  this  ink,  a  white 
precipitate  of  pure  silver  is  procured,  by  dissolving  that  metal  in  ni- 
tric acid,  and  afterwards  separating  it  from  its  alloy ^  by  suspending  in 
the  solution,  a  thin  slip  of  copper,  which  by  its  greater  affinity  for 
the  acid,  throws  down  the  silver  in  the  form  of  a  white  powder,  which 
powder  being  afterwards  mixed  with  an  aqueous  solution  of  white 
glue  and  gum  arable,  forms  the  ink.  But  to  render  this  preparation 
effectual,  thelinen,  Sec. to  which  it  is  applied  by  the/j<?n,  must  have  pre- 
viously received  an  impregnation  like  some  of  those  which  I  have  re- 
cently described,  though  they  are,  in  this,  rendered  less  necessary,  be- 
cause the  precipitate  of  silver  retains  but  a  small  proportion  of  acid, 
as  is  manifested  by  its  want  of  solubility  in  water,  which  makes  it 
expedient  to  shake  the  mixture  as  often  as  it  is  used.  The  impregna- 
tion most  commonly  employed  seems  to  consist  of  isinglass,  and 
"white  animal  glue  dissolved  in  spirit  of  wine,  which  being  applied 
to  the  part  intended  to  be  marked,  is  suffered  to  dry;  after  which 
it  is  fit  to  be  written  upon  with  what  is  called  the  ink.  Additional 
means  havesometimes  been  employed  to  increase  the  blackness  of 
the  latter,  but  their  effect  will  not  last. 


Philosophy  of  Permanent  Colours.  247 

potash  and  spirit  of  wine,  it  also  produced  a  black,  which 
disappeared  like  the  former;  and  with  caustic  vegetable 
alkali  it  produced  nearly  the  same  effect.  With  orpiment, 
dissolved  by  potash,  it  produced  a  very  deep  black,  which 
stood  two  or  three  weeks  exposure  to  the  weather;  after 
which  the  mercury  began  to  revive,  in  very  small  glo- 
bules, and  the  colour  to  disappear  in  spots.*^ 

Platina, 

This  metal  was  first  discovered  at  Choco  and  Santa 
Fe,  in  South  America,  and  was  not  known  to  exist  na- 
turally in  any  other  place,  until  Vauquelin  lately  detected 
it  among  the  grey  silver  ores  of  Guadalcanal  in  Estre- 
madura;  and  more  recently  Dr.  Wollaston  has  examined 
and  described  a  small  specimen,  which  had  been  found 
in  Brazil,  intermixed  with  palladium.  See  Phil.  Trans. 
1809. 

Proust  says,  the  result  of  a  solution  of  platina  in  the 
nitro-muriatic  acid,  is  (like  that  of  gold  so  dissolved)  a 
pure  and  simple  muriate. 

The  oxide  of  platina,  at  the  maximum  of  oxygenation, 
is  of  a  yellowish  brown  colour;  but  when  heated  and 
deprived  of  about  one  half  of  this  portion  of  oxygene, 
it  becomes  green. 

*  I  have  now  before  me  some  very  black  writing  upon  calico, 
which  states  itself  to  have  been  written  with  a  solution  of  nitrate 
of  quicksilver,  upon  calico  impregnated  by  a  mi'xture  of  soda,  liver 
of  sulphur,  and  sugar,  in  water:  seventeen  years  have  elapsed  since 
this  writing  was  performed,  and  there  is  no  appearance  of  that  re- 
vivification  of  the  mercury,  which  I  had  experienced  when  it  was 
used  upon  calico  with  impregnations  differing  but  little  from  that 
last  mentioned. 

Professor  Gmelin  of  Gottingen,  in  his  publication,  "  de  tingendo 
per  nitri  acidum,"  &c.  mentions  the  staining  of  silk  with  a  cofificr 
colour  by  mercury,  dissolved  in  nitric  acid. 


248  Philosophy  of  Permanent  Colours. 

Having  immersed  a  bit  of  fine  calico  in  a  diluted  so- 
lution of  platina,  by  nitro-muriatic  acid,  it  acquired  a 
yellowish  orange  colour,  and  this  being  afterwards  driedy 
I  dipped  it  into  a  diluted  solution  of  tin  by  muriatic  acid, 
to  see  what  effect  would  result  from  an  abstraction  of 
oxygene  (which  I  expected)  by  the  latter;  and  to  my 
surprise,  I  saw  the  colour  instantaneously  changed  to 
that  of  arterial  blood.  This  calico  being  afterwards 
dried  and  washed  with  soap,  its  beautiful  red  was  there- 
by made  to  incline  very  much  to  a  bright  full  orange 
colour,  which  did  not  change  by  subsequent  washings, 
and  seems  to  be  permanently  fixed.  Though  somewhat 
costly,  it  probably  may  be  susceptible  of  some  useful 
application  to  fine  muslins  in  calico  printing.  In  the 
production  of  this  colour,  the  solution  of  tin  seems  to 
act  as  it  does  in  producing  a  purple  with  gold. 

The  solution  of  platina  (without  that  of  tin)  being 
applied  to  calico,  produced  a  yellow  colour,  which, 
when  washed,  seemed  to  be  permanent,  though  it  was 
afterwards  raised  to  a  bright  high  orange,  by  applying 
to  it  the  solution  of  tin  last  mentioned. 

The  same  solution  of  platina,  being  applied  to  calico, 
which  had  been  soaked  in  a  prussiate  of  lime,  produced 
a  brown  colour,  which,  by  washing  with  soap,  became 
a  dark  violet,  which  seems  to  be  permanently  fixed. 
Similar  effects  were  afterwards  produced  by  the  prus- 
siate of  potash. 

Other  pieces  of  calico  impregnated  severally  with 
sulphuret  of  potash;  with  soda,  and  the  acidulous  ar- 
seniate  of  potash;  with  orpiment  dissolved  by  liquid 
potash;  with  liver  of  sulphur  and  alcohol;  and  with  lint- 
seed  oil;  and  afterwards  soaked  in  the  before-mentioned 
solution  of  platina  diluted,  acquired  different  shades  of 
purple,  olive,  and  brown  colours,  which,  when  washed 
with  soap,  appeared  to  be  permanently  fixed. 


Philosophy  of  Permanent  Colours.       '      249 

Manganese. 
The  great  variety  and  mutability  of  colours  aiForded 
to  water,  in  different  proportions,  and  of  different  tem- 
peratures, by  manganese  in  combination  with  potash, 
was  long  since  observed  by  Glauber,  as  is  noticed  at 
page  13  of  this  volume.  Whether  the  alkaline  solutions 
of  this  oxide  are  capable  of  being  usefully  employed  to 
dye  substantive  colours,  I  am  unable  to  decide;  my  ex- 
periments therewith  having  been  too  {t\\.  I  have  found, 
however,  that  a  considerable  variety  of  lasting  brown, 
or  dark-coloured  stains,  may  be  produced  upon  bits  of 
linen  and  cotton,  which  have  previously  and  severally 
received  the  different  impregnations  before  mentioned, 
by  applying  to  them  a  diluted  sulphate  of  manganese; 
and  without  any  such  impregnation,  if  the  latter  be 
applied  to  linens  or  cottons,  and  they  be  afterwards 
dipped  into  a  weak  solution  of  potash  or  soda,  a  yel- 
lowish brown  colour  will  be  produced;  and  this,  by 
attracting  oxygene,  will  gradually  change  to  a  dark^  and 
very  durable  brown.  But  if  to  this  otherwise  lasting  dark 
colour,  a  solution  of  tin  by  muriatic  acid  be  applied,  it 
will  restore  the  former  yellowish  brown,  by  causing  an 
abstraction  of  oxygene  from  the  manganese;  though  the 
latter  by  its  affinity  for  oxygene  will  afterwards  repair 
this  loss,  and  by  doing  so  will  restore  the  former  dark 
brown  colour. 

Cobalt. 

The  nitrate  of  cobalt  may  be  decomposed  by  liquid 
potash,  and  it  will  then  afford  a  blue  precipitate,  which 
if  secluded  from  atmospheric  air  will  become  violet,  and 
afterwards  red. 

Nitrate  of  cobalt  applied  to  cotton,  impregnated  with 

Voi.  L  2  1 


250  Philosophy  of  Permanent  Colours, 

soda,  with  soda  and  acidulous  arseniate  of  potash,  and 
with  caustic  vegetable  alkali,  produced  lively  pink  and 
rose  colours,  which  stood  washing  and  exposure  to  wea- 
ther for  a  considerable  time. 

The  oxide  of  cobalt,  dissolved  by  muriatic  acid,  and 
applied  to  cotton  impregnated  with  soda,  when  held  to 
the  fire,  exhibited  the  most  beautiful  green,  which,  as 
the  cotton  cooled,  changed  to  an  apple-green;  then 
passed  through  all  the  shades  of  yellow,  and  became 
a  kind  of  pale  buff  colour,  which  the  oxide  retained 
after  the  cotton  had  been  washed  with  soap;  but  then 
on  being  heated,  it  was  found  to  have  lost  the  property 
of  becoming  green,  though  on  dipping  it  into  a  diluted 
muriatic  acid,  it  immediately  regained  and  exhibited 
the  same  property.  These  effects  are  connected  with 
those  which  similar  solutions  of  cobalt  produce  as  sym- 
pathetic inks;  though  I  confess  myself  dissatisfied  with 
all  the  explanations  hitherto  given  of  them.  The  pre- 
sence of  muriatic  acid  is  essential  to  their  existence,  the 
nitrate  of  cobalt  producing  no  such  phenomenon;*  nor 
did  I  find  that  the  presence  or  absence  of  light  had  any 
effect  in  retarding  or  promoting  any  of  the  changes  of 
colour  here  mentioned. 

*  Having  lately  soaked  a  bit  of  calico  in  a  diluted  nitrate  of  cobalt, 
it  exhibited  a  pale  rose  colour,  when  dried.  To  the  calico  so  coloured 
I  applied  a  solution  of  tin  by  muriatic  acid,  in  ftfiots<i  and  afterwards 
holding  the  calico  to  the  fire,  I  soon  observed  that  these  spots  were 
all  of  a  most  beautiful  blyeish  green^  whilst  every  other  part  retained 
its  rose  colour.  By  removing  the  calico  from  the  fire,  and  letting 
it  cool,  the  spots  again  became  rose-coloured.  Having  afterwards 
rinced  the  calico  in  water,  the  parts  which  had  been  spotted  lost  the 
power  of  becoming  green  when  heated;  but  by  wetting  them  with 
muriatic  acid,  they  regained  this  power,  a  proof  that  this  acid,  and 
not  the  tin  dissolved  by  it,  had,  in  the  first  instance,  enabled  the  fire 
to  produce  the  blueish  green  colour. 


Philosophy  of  Permanent  Colours,  251 

Nickel, 

If  this  metal  be  dissolved  by  nitric  acid,  the  solution 
may  be  decomposed  by  potash,  and  a  grass-green  hy- 
drated  oxide  will  be  thereby  obtained.  By  impregnating 
calico  with  a  mixture  of  soda  and  sugar,  and  immersing 
it  in  a  diluted  solution  of  nickel  by  the  nitric  acid,  a 
similar  green  was  produced  on  the  calico;  but  it  did 
not  prove  sufficiently  durable,  to  be  employed  in  dyeing 
or  calico-printing. 

Molybdena,  titanium,  palladium,  and  osmium,  afford 
coloured  oxides  of  considerable  beauty  and  variety, 
which  probably  might  be  applied  and  fixed  upon  silk, 
linen,  and  cotton,  were  not  these  metals  too  scarce  and 
costly,  especially  the  latter,  for  this  use. 

BerthoUet  has  mentioned,  (Ann.  de  Chimie,  tom.  i.) 
that  the  simple  mixture  of  an  oxide  of  lead  with  lime, 
will  blacken  wool,  hair,  &c.;  and  that  some  persons  have 
used  it  to  render  grey  hairs  black.  Wishing  to  ascertain 
its  effect  in  dyeing,  I  boiled  flannel  in  lime-water  with 
litharge,  which  produced  a  tolerable  black  upon  the 
flannel;  and  this  black  was  not  diminished  by  washing 
the  flannel  with  soap,  and  exposing  it  for  the  usual  time 
to  the  weather:  strong  acids,  however,  dissolved  the  lead, 
and  discharged  the  colour:  and  the  lime  was  found  to 
have  weakened  the  texture  of  the  flannel  considerably, 
and  more  especially  when  orpiment  was  added;  an  effect 
similar  to  that  which  it  produces  in  those  depilatory  com- 
positions which  were  brought  to  Europe  from  Turkey. 

Perhaps  my  readers  may  think,  that  many  of  the  pre- 
ceding experiments  are  such  as  the  great  Bacon  (Lord 
Verulam)  has  termed  "  experiments  of  light  rather  than 
of  fruit  "  But  such  experiments  are  not  to  be  neglected 
in  a  work  which  professes  to  treat  of  the  Philosophy  of 


252  Philosophy  of  Permanent  Colours* 

Colours,  though  they  should  not  be  susceptible  of  any 
considerable  practical  advantage,  or  application. 

With  this  observation,  I  finish  my  account  of  sub- 
stantive colouring  matters.  They  claimed  my  earliest 
notice,  because  their  properties  and  modes  of  applica- 
tion are  generally  the  most  simple  and  intelligible;  and 
because  some  of  them,  particularly  the  oxides  of  metals^ 
may  also  be  made  to  serve  as  the  bases  of  adjective 
colours,  which  v^ill  become  the  subject  of  our  next 
inquiries. 


END  OF  PART  1. 


EXPERIMENTAL.  RESEARCHES 


COKC£RKIKO  TH£ 


PHILOSOPHY 


PERMANENT  COLOURS, 


PART  II, 


CHAPTER  I. 

Of  Adjective  Colours  generally,  and  their  bases;  with  an 
illustration  of  their  effects  upon  each  other,  as  exem- 
plifed  by  Oriental  and  European  calico-printing, 

**Les  faits  sont  de  tous  les  tenips,  ils  sont  iinmuables,  comrae  la  nature  dont  ils  sont 
"  le  langage;  mais  les  consequences  doivent  varier  selon  l*6tat  des  connoissances 
**  acquises.*'  Cuaptai,  El^mens  de  Cfumie, 

Adjective  colouring  matters  are  generally  soluble, 
in  a  great  degree  at  least,  by  water;  though  some  of 
them  derive  their  solubility  from  an  intermixture  of 
what  has  been  called  extractive  matter;  which  being 
separated  in  the  dyeing  process,  after  the  adjective  co- 
lour has  been  applied  to  the  dyed  substance,  their  union 
becomes  thereby  more  intimate  and  permanent.  But  in 
other  respects,  adjective  colours  owe  their  durability, 
as  well  as  their  lustre,  to  the  interposition  of  some 
earthy  or  metallic  basis;  which,  having  a  considerable 
attraction,  both  for  the  colouring  matter  and  the  stuflf 
to  be  dyed,  serves  as  a  bond  of  union  between  them, 
and  obviates  that  disposition  to  suffer  decomposition 
and  decay,  which  naturally  belongs  to  such  colouring 


254  Philosophy  of  Permanent  Colours, 

matters  when  uncombined.  These  earthy  and  metallic 
bases,  having  been  commonly  employed  in  a  state  of 
solution  or  combination  with  acids,  were  from  that  cir- 
cumstance denominated  mordants  (biters  or  corroders) 
by  the  French,  who,  indeed,  began  to  employ  the  term 
long  before  any  thing  like  a  true  theory  of  dyeing  had 
been  conceived;  whilst  even  alum  was  supposed  to  act 
by  its  sulphuric  acid,  and  not  by  the  pure  clay  upon 
which  its  usefulness  depends,  and  whilst  in  truth  all  the 
other  matters  called  mordants  were  supposed  to  be  use- 
ful only  by  their  solvent  or  corroding  powers;  and  the 
term,  having  been  thus  employed,  has  been  since  adopt- 
ed in  other  countries.  The  ingenious  Mr.  Henry,  of 
Manchester,  has,  however,  lately  objected  to  it,  with 
great  reason,*  and  proposed  in  its  stead  to  employ  the 
term  basis,  which  seems  defective  only,  inasmuch  as  it 
does  not  express  the  particular  affinity,  or  power  of  at- 
traction, manifestly  subsisting  between  these  earthy  and 
metallic  substances,  and  the  several  adjective  colouring 
matters,  as  well  as  between  the  former  and  the  fibres  of 
wool,  silk,  cotton,  &c.  I  confess,  however,  that  no  other 
more  suitable  term  has  occurred  to  me;  and  being  un- 
willing to  propose  new  terms,  without  some  cogent  rea- 
son, I  shall  sometimes  employ  that  of  mordant  as  well 
as  that  of  basis;  though  not  indiscriminately  in  all  cases; 
since  I  shall  generally  use  the  former  to  signify  earthy 
and  metallic  substances  when  actually  dissolved  by  some 
acid,  alkaline,  or  other  solvent,  and  when  of  course  they 
will  commonly  prove  more  or  less  corroding  or  biting, 
according  to  the  original  meaning  of  the  term.  But  the 
denomination  of  basis  will  be  most  frequently  used  to 
designate  the  same  earthy  and  metallic  substances,  dis- 

-*  See  his  "  Considerations  relative  to  the  nature  of  Wool,  Silk, 
and  Cotton,  as  objects  of  the  Art  of  Dyeing,  &c."  in  the  third  yol. 
of  the  Memoirs  of  the  Manchester  Society. 


Philosophy  of  Permanent  Colours.  255 

tinctly  and  separately  from  any  acid  or  other  solvent, 
when  actually  fixed  in  the  pores  or  fibres  of  wool,  silk, 
&c.  or  when  it  is  not  intended  to  notice  any  property 
in  them,  which  may  more  immediately  result  from  their 
combinations  with  any  particular  menstruum.  M.  Ber- 
thollet,  indeed,  gives  the  term  mordant  a  much  more 
extensive  signification,  as  meaning  all  the  different  che- 
mical agents  capable  of  serving  as  intermedia  between 
the  several  colouring  particles  and  the  stuffs  so  dyed 
with  them,  either  for  the  purpose  of  assisting  their 
union,  or  of  modifying  it.*  This  last  effect  (of  modifi- 
cation) may,  however,  be  produced  by  a  variety  of  mat- 
ters besides  those  which  are  of  the  earthy  or  metallic 
kinds,  and  indeed  by  every  thing  capable,  not  of  fixing, 
but  of  merely  varying,  the  shades  of  adjective  colouring 
matters.  These,  therefore,  I  think  it  more  proper  to  de- 
signate, not  as  mordants  or  bases,  but  as  alterantSy-\ 
whose  use  and  application  may  in  this  respect  be  ex- 
tended to  substantive  as  well  as  to  adjective  colours. 

The  bases  pre-eminently  useful  with  adjective  co- 
lours, are  the  earth  of  alum,  and  the  oxides  of  tin  and 
iron,,  held  or  applied  in  solution  by  an  acid  menstruum; 
and,  excepting  the  process  for  dyeing  black  upon  wool- 
lens and  silks,  it  is  generally  deemed  most  advantageous 
to  combine  these  bases  first,  and  separately,  with  the 
stuffs  to  be  dyed,  superadding  the  colouring  matters 
afterwards;  because  the  affinity  or  attraction  of  the  basis, 
is  commonly  greater  for  the  latter,  than  for  either  wool, 

*  "L'on  donne  le  nom  de  mordant  aux  substances  qui  servent 
d'interntiedes  entre  les  parties  colorantes  et  les  etoffes  que  i*on 
teint,  soit  pour  faciliter  leur  combinaison,  soit  pour  la  modifier." 
Elemena  de  fArt  de  la  Tmnture^  torn.  i.  p.  26,  of  the  first  edition. 

t  M.  Berthollet,  in  his  last  edition,  torn.  i.  p.  71,  has  adopted  the 
term  of  alterants^  and  employed  it  in  the  way  which  I  had  sug- 
gested, as  above,  in  my  first  publication, 


256  Philosophy  of  Permanent  Colours. 

silk,  cotton,  or  linen;  particularly  that  of  the  earth  of 
alum,  which,  when  applied  subsequently  to,  and  upon 
the  colouring  matter,  forms  with  it  a  kind  of  lake,  by 
which  their  respective  affinities  are  in  a  great  degree 
exerted  towards,  and  saturated  by  each  other;  and  the 
size  of  their  particles  being  thereby  increased,  they  do 
not  penetrate  copiously  into,  nor  combine  intimately 
with  the  fibres  of  wool,  silk,  &c.;  but  remain  in  a  great 
degree  suspended  in  the  dyeing  liquor,  or  precipitated 
to  the  bottom  of  it.  But  by  combining  the  basis  pre- 
viously^  and  separately,  with  the  stuff  to  be  dyed,  and 
afterwards  applying  the  colouring  matter,  this  last,  when 
so  applied,  is  powerfully  attracted  by  the  conjoined  affi- 
nities of  the  former,  so  that  the  dyeing  liquor  may  be 
completely  exhausted,  and  made  colourless  thereby. 

It  must,  however,  be  noticed  in  regard  to  wool^  that 
by  reason  of  its  greater  attraction  for  metallic  oxides, 
they  may,  without  any  considerable  disadvantage,  be 
applied  to  it,  in  conjunction  with  adjective  colouring 
matters,  as  will  be  mentioned  in  regard  to  the  dyeing  of 
scarlet  and  some  other  colours.  It  ought  also  to  be  ob- 
served, that  when  colours  are  dyed  upon  wool,  silk,  &c. 
by  the  aid  of  an  aluminous  or  metallic  basis,  the  colour 
is  applied,  or  dyed  more  immediately  upon  the  latter, 
than  upon  the  wool  or  silk,  &c.  as  will  be  made  evident 
hereafter.  The  durability  therefore  of  an  adjective  colour 
must  depend,  not  only  on  the  natural  stability  of  the 
colouring  matter,  but  also  upon  the  energy  of  its  affini- 
ties, both  for  the  stuff  which  is  dyed,  and  for  the  basis 
or  intermedium  upon  which  it  is  immediately  applied, 
and  which,  by  its  own  peculiar  attractions,  binds  them 
to  each  other. 

The  true  nature  and  uses  of  mordants  or  bases,  for 
the  purposes  under  consideration,  can,  I  believe,  in  no 
way  be  so  distinctly  manifested,  or  so  clearly  illustrated. 


Philosophy  of  Permanent  Colours.  257 

as  by  their  effects  in  what  I  shall  call  topical  dyeing,  or 
that  species  of  it  by  which  different  colours  are  com- 
municated to  particular  spots  or  figures  on  the  same 
piece  of  cotton  or  linen,  according  to  the  several  bases 
previously  applied  thereto,  and  which  principally  con- 
stitutes that  truly  wonderful  art,  the  art  of  calico-print- 
ing. I  shall,  therefore,  in  this  place,  bring  under  my 
reader's  notice  some  of  the  more  important  operations 
of  that  art,  reverting  at  the  same  time,  as  far  as  we  can, 
towards  its  remote  origin,  in  order  to  see  how,  and  by 
what  means,  it  has  attained  its  most  important  improve- 
ments. 

Pliny  describes  the  Egyptians  as  practising  a  species 
of  topical  dyeing,  or  calico-printing,  which,  as  far  as  can 
be  discovered  from  his  general  terms,  appears  to  have 
been  similar  to  that  which,  many  ages  after,  was  found 
to  exist  in  Hindostan  and  other  parts  of  India,  and  was 
from  thence  introduced  into  this  and  other  countries  of 
Europe.  He  says,  the  Egyptians  began  by  painting  or 
drawing  on  white  cloths,  (doubtless  linen  or  cotton,) 
with  certain  drugs,  which  in  themselves  possessed  no 
colour,  but  had  the  property  of  attracting  or  absorbing 
colouring  matters.  After  which,  these  cloths  were  im- 
mersed in  a  heated  dyeing  liquor;  and  though  they  were 
colourless  before,  and  though  this  dyeing  liquor  was  of 
one  uniform  colour,  yet  when  taken  out  of  it  soon  after, 
they  were  found  to  be  wonderfully  tinged  of  different 
colours,  according  to  the  different  natures  of  the  several 
drugs  which  had  been  applied  to  their  different  parts; 
that  these  colours,  so  wonderfully  produced  from  a  tinc- 
ture of  only  one  colour,  could  not  be  afterwards  dis- 
charged by  washing;  and  he  considers  it  as  admirable, 
that  the  dyeing  liquor,  which,  if  cloths  of  different  co- 
lours had  been  put  into  it,  would  have  confounded  them 

Vol.  I.  2  K 


258  Philosophy  of  Permanent  Colours. 

all,  should  thus  produce  and  permanently  fix  several 
colours,  being  itself  only  of  one.* 

Whether  the  Egyptians  borrowed  this  wonderful  art 
from  the  Hindoos  and  other  inhabitants  of  India,  or 
whether  the  latter  borrowed  it  from  the  Egyptians,  is  a 
question  which  probably  may  be  answered  without 
much  difficulty,  if  we  consider  the  many  reasons  which 
exist  for  believing  that  this  art  has  been  practised  over 
a  great  part  of  India  during  a  long  succession  of  ages; 
that  not  only  the  art  itself  subsisted  there,  but  that  the 
colouring  and  other  materials  for  exercising  it,  were  the 
natural  and  peculiar  productions  of  that  country,  rather 
than  of  Egypt;  that  the  Indians  were  highly  civilized  at 
least  twenty-two  centuries  ago,  during  which  space  of 
time  their  manners,  sanctified  (if  I  may  so  express  my- 
self) by  being  connected  to  their  religion,  suffered  little, 
perhaps  no  change;  that  their  trades  were  carefully  per- 
petuated in  particular  families;  and  also  that  among  these 
their  manufactures  were  undoubtedly  of  very  great  anti- 
quity, whilst  obvious  ways,  by  which  they  might  have 
been  easily  extended  to  Egypt,  and  other  countries, 
undoubtedly  existed  long  before  the  time  when  Pliny 
wrote. 

Major  Rennell  observes,  that  "  a  passion  for  Indian 
"  manufactures  and  products  has  actuated  the  people 
"  of  every  age,  in  lower  Asia,  as  well  as  in  the  civilized 

*  "  Pingunt  et  vestes  in  -Egypto  inter  pauca  mirabili  genere, 
<'  Candida  vela  postequam  attrivere  illinentcs  non  coloribus,  sed  co- 
"  lorem  sorbentibus  medicamentis:  hoc  cum  fecere,  non  apparet  in 
**  velis:  sed  in  cortinam  pigmenti  ferventis  mersa,  post  momentum 
"  extrahuntur  picta.  Mirumque,  cum  sit  unus  in  cortina  color,  ex 
"  illo  alius  atque  alius  fit  in  veste,  accipientis  medicamenti  qualitate 
"  mutatus:  nee  postea  ablui  potest.  Ita  cortina  non  dubia  confusura 
"  colores  si  pictos  acciperet,  digeret  eos  ex  uno,  pingitque  dum  co- 
<^  quit."  Plinii,  I.  xxxv.  cap.  ii. 


Philosophy  of  Permanent  Colours.  259 

**  parts  of  Europe;  the  delicate  and  unrivalled,  as  well 
**  as  the  coarser  and  more  useful  fabrics  of  cotton  of 
"  that  country,  particularly  suiting  the  inhabitants  of  the 
**  temperate  regions  along  the  Mediterranean  and  Eux- 
**ine  seas.  To  this  trade  (continues  he)  the  Persian  and 
*'  Arabian  Gulfs  opened  an  easy  passage;  the  latter  par- 
"  ticularly,  as  the  land  carriage  between  the  Red  Sea 
"  and  the  Nile,  and  between  the  Red  Sea  and  the  Me- 
"  diterranean,  took  up  only  a  few  days.  It  is  highly  pro- 
*'  bable,  and  tradition  in  India  warrants  the  belief  of  it, 
"  that  there  was  from  time  immemorial  an  intercourse 
"  between  Egypt  and  Hindostan,  at  least  the  maritime 
'*  part  of  it;  similarity  of  customs  in  many  instances,  as 
*^  related  of  the  ancient  Egyptians  by  Herodotus,  (and 
"  which  can  hardly  be  referred  to  physical  causes,)  ex- 
"  isting  in  the  two  countries." — ^'  It  would  appear,  that 
"under  the  Ptolemies  the  Egyptians  extended  their 
*'  navigation  to  the  extreme  point  of  the  Indian  Conti- 
*'  nent,  and  even  sailed  up  the  Ganges  to  Palibothra." 
See  Memoir  and  Map  of  Hindostan,  &c.  4to.  by  James 
Rennell,  F.R.S. 

The  best  accounts  of  the  practice  of  calico-printing^ 
in  the  East  Indies,  were  given  in  certain  letters,  written 
by  Father  Ccetirdoux,  a  missionary  at  Pondicherry, 
(pubUshed  in  the  26th  volume  of  "  Recueil  des  Let- 
*'tres  Ediliantes,  &c.")  with  the  supplemental  remarks 
and  corrections  of  Mons.  Poivrc;  and  in  a  manuscript 
account  procured  from  thence  by  Mons.  Du  Fay,  and 
communicated  to  the  Royal  Academy  of  Sciences  at 
Paris,  by  the  Abbe  Mazeas;t  and  also  in  the  report 

*  I  here  continue  to  use  this  term,  though  in  truth  none  of  the 
mordants  or  colouring  matters,  employed  to  stain  the  calicoes  of 
India,  were  applied  by  engraved  blocks  or  plates  as  in  Europe,  but 
by  the  pencil. 

t  "  Recherches  sur  la  cause  physique  de  Tadherence  de  la  ecu- 


260  Philosophy  of  Fermanent  Colours. 

ttiade  in  1735  by  M.  Beaulieu,  (then  a  captain  in  the 
French  navy),  of  the  operations  which,  at  the  request 
of  Du  Fay,  he  caused  to  be  performed  under  his  own 
inspectioriy  at  Pondicherry,  and  by  which  a  piece  of 
chintz  was  completely  printed  or  stained  of  various  co- 
lours, as  described  in  a  little  publication,  entitled, 
*'  Traite  sur  les  toiles  peintes,  dans  Icquel  on  voit  la 
maniere  dont  on  les  fabrique  aux  Indes,''  &.c.  From 
these  several  accounts,  as  well  as  from  some  valuable 
private  information  which  I  have  been  able  to  procure, 
the  following  concise  statement  has  been  composed,  of 
the  principal  operations  by  which  the  chintz  calicoes  of 
India  received  the  colours  for  which  they  were  highly 
Celebrated  before  the  art  of  calico-printing  had  been  in- 
troduced and  simplified  in  Europe.  The  cotton  cloths, 
when  brought  from  the  weaver,  partly  bleached,  were 
worn  next  to  the  skin,  by  the  dyer  and  his  family,  during 
the  space  of  eight  or  ten  days;  after  which  they  under- 
went several  macerations  in  water  with  goat's  or  sheep's 
dung,  accompanied  by  frequent  intermediate  beatings, 
washings,  and  dryings  (by  exposure  to  the  sun.)  After- 
wards they  were  soaked  for  some  time  in  a  mixture  of  the 
astringent  external  part  of  the  fruit  of  the  yellow  myro- 
balan  tree,*  (separated  from  the  nut  and  powdered)  with 

Jeur  rouge  aux  toiles  peintes  qui  nous  viennent  dee  cotes  de  Mala- 
bar et  de  Coromandeh"  par  M.  TAbbe  Mazeas,  correspondant  dc 
TAcademie,  &c.  Mem.  des  S9avans  Etrangers,  torn.  iv. 

*  The  fruits  of  several  trees  not  yet  accurately  distinguished,  or 
ascertained,  have  been  called  myrobalans:  that  species  which  is 
here  meant,  belongs  to  the  genus  terminalia^  to  which  the  trivial 
or  specific  name  of  chebula,  or  that  of  citrina  has  been  applied. 
See  Retzius's  Observations.  It  is  the  badamier  of  the  French,  and 
her  of  the  Hindoos.  The  ripe  fruit  is  yellow,  and  pear-shaped,  with 
five  longitudinal  angles;  and,  when  dried,  appears  wrinkled,  it  con- 
sists of  a  white  pentangular  nut,  covered  by  a  mucilaginous  and 
highly  astringent  substance,  nearly  two  lines  in  thickness;  and 


Philosophy  of  Permanent  Colours^  261 

buffaloes'  milk;  and  being  thoroughly  penetrated  and  im- 
pregnated therewith,  they  were  taken  out,  and  the  liquor 
being  well  squeezed  from  them,  they  were  again  dried 
bv  exposure  to  sun- shine,  and  afterwards,  by  pressure 
and  friction,  with  wooden  rollers,  they  were  made 
smooth  enough  to  be  drawn  upon  by  the  pencil,  with 
the  different  mordants  (according  to  patterns  previously 
traced  out  and  marked  by  powdered  charcoal).  The 
first  of  these  mordants  was  an  iron  liquor  (acetite  of 
iron),  similar  to  that  since  employed  by  the  calico- 
printers  of  Europe,  excepting  only  that,  instead  of  vine- 
gar or  alegar,  the  iron  was  dissolved  by  a  mixture  of 
sour  palm  wine,  and  of  water  in  which  rice  had  been 
boiled.*  This  liquor  was  applied  to  the  figures  or  spots 

within  the  nut  is  a  small  white  oily  kernel.  The  nuts  are  separated 
from  the  astringent  substance  which  covers  them,  by  bruising  the 
fruit  under  a  wooden  roller  or  cylinder,  it  being  the  external  astrin- 
gent substance  only,  or  an  infusion  or  decoction  thereof,  which  is 
generally  employed  throughout  India  for  dyeing  or  calico-printing, 
and  which,  by  very  decisive  experiments,  to  be  mentioned  here- 
after, I  have  found  to  be  capable  of  answering  all  the  purposes  of 
galls.  Indeed  the  leaves  of  this  tree  afford  a  sort  of  flaitish  yellow 
irregular  ^a//«,  produced  by  the  punctures  of  a  particular  species 
of  insect;  which  galls  are  collected  and  sold  in  all  the  bazars  or 
markets:  they  are  called  aldecay  by  the  Telingas,  or  Hindoos  of  the 
Circars,  and  cadacay  or  caducay  by  the  Tamuls:  and  they  produce 
with  iron  a  strong  durable  black  dye,  and  ink;  and  with  alum  a  very 
full,  though  dark  brownish  yellow.  If  these  galls  were  bruised  so 
as  to  occupy  less  space  than  they  otherwise  must,  by  reason  of  the 
cavities  contained  within  them,  they  might  be  advantageously  im- 
ported into  this  country,  as  might  also  the  external  astringent  sub- 
stance of  the  fruit  of  the  terminalia  chebula  separated  from  its  use^ 
less  nut.  By  some  persons  the  unripe  fruit  is  preferred,  as  having 
most  acerbity  or  astringency. 

*  In  the  letters  of  Father  Cceurdoux,  the  water  in  which  rice 
had  been  boiled,  and  which  was  converted  to  a  sort  of  vinegar,  is 
termed  canje,  and  the  vinegar  from  palm  wine  is  named  callou.  In 
these,  bits  of  old  iron  and  the  vitrified  matter  of  a  smith's  forge 


262  Philosophy  of  Permanent  Colours, 

intended  to  be  made  black,  by  a  combination  of  the 
oxide  of  iron,  with  the  colouring  matter  of  the  myro- 
balans. 

By  this  method  of  producing  black  stains,  the  colour- 
ing matter  is  applied  previously  to  the  metallic  basis, 
contrary  to  the  practice  in  regard  to  most  other  colours. 
But  in  this  the  strong  attraction  of  oxide  of  iron  for  the 
fibres  of  cotton,  as  already  mentioned,  obviates  the  evil 
which  would  result  from  a  similar  application,  where 
other  mordants  were  intended  to  follow. 

When  the  black  figures  or  stains  have  been  thus  pro- 
duced, the  blue  are  next  to  be  given,  and  as  a  prepara- 
tion for  this,  it  is  tliought  necessary  to  remove  the  as- 
tringent and  oily  matters  which  the  calico  had  imbibed 
in  every  part,  by  being  soaked  in  the  mixture  of  buffa- 
loes' milk,  and  powder  of  myrobalans;  and  for  this  pur- 
pose it  is  macerated  during  twenty-four  hours  in  the 
dung  of  goats,  or  sheep,  diluted  with  water,  then  rinced 
thoroughly  and  repeatedly  in  clean  water,  and  dried  in 
the  sun:  after  which  the  figures  intended  to  be  made 
blue,  are  marked  by  outlines  traced  with  powdered 
charcoal  mixed  with  a  solution  of  gum;  and  this  being 
done,  every  other  part  not  intended  to  be  made  blue,  is 
covered  w^ith  melted  wax,  to  protect  it  from  the  indigo: 
and  then  the  calico  is  sent  to  the  blue  dyer,  and  by  him 
immersed  in  the  ^ro/f/ indigo  vat  described  at  p.  15  Ij  and 
being  sufficiently  dyed,  the  wax  is  afterwards  removed 
by  covering  the  calico  with  boiling  water,  which  melts 
the  wax,  and  this  last  rising  to  the  top,  is  separated 
when  the  water  cools.  But  as  the  wax  cannot  in  this 

powdered,  were  macerated  and  exposed  to  the  sun,  until  a  sufficient 
solution  had  been  efflected.  According  to  Dr.  Roxburgh,  the  Te- 
lingas  gives  the  name  of  cassim  to  their  solution  of  iron,  made  by 
palmira  toddy,  or  the  juice  of  Borassus  flabelliformis,  (a  species  of 
palm)  turned  to  vinegar. 


Philosophy  of  Permanent  Colours.  263 

way  be  completely  removed,  the  calico  is  again  soaked 
in  a  mixture  of  goat's  or  sheep's  dung  and  water, 
rinccd,  dried  in  the  sun,  beat  and  afterwards  soaked  and 
boiled  in  water  with  olla,  or  washermen's  earth,  (which 
seems  to  be  a  natural  mixture  of  soda  and  chalk)  then 
macerated  in  water  with  cow-dung,  and  again  well 
rinced,  dried  in  the  sun,  and  beat.  After  all  these  ope- 
rations, the  calico  is  again  to  be  impregnated  with  the 
same  oily  and  astringent  matters  which  were  removed 
to  make  way  for  the  indigo  blue,  by  soaking  it  again  in 
the  mixture  of  buffaloes'  milk  and  myrobalan  powder, 
drying  and  making  it  smooth,  as  before.  And  this  being 
done,  the  calico  will  be  in  a  fit  condition  to  receive  the 
aluminous  mordant,  upon  which  the  red  is  afterwards  to 
be  dyed;  which  mordant  is  to  be  applied  according  to 
figures  marked  out  with  powdered  charcoal:  and  when 
purple  and  violet  figures  are  to  be  produced,  they  are  to 
be  in  like  manner  designated;  and  for  these,  a  mixture 
of  the  solution  of  iron,  with  the  aluminous  mordant,  in 
suitable  proportions,  is  to  be  applied;  whilst  for  the 
figures  intended  to  be  red,  the  aluminous  mordant  alone 
is  employed  as  a  basis.  These  mordants  are  commonly 
applied  by  children,  with  the  pencil,  or  with  pointed 
wooden  sticks. 

To  prepare  this  aluminous  mordant,  two  ounces  of 
alum  were  dissolved  in  two  quarts  of  water,  taken  from 
certain  pits,  which  water  Father  Coeurdoiix  has  called 
"apre,"  probably  because  it  held  in  solution  a  little 
soda,  which  there  abounds  in  many  places.  To  colour 
this  solution,  so  that  the  strokes  of  the  pencil  in  apply- 
ing it  might  be  visible,  a  little  sappan  or  sampfan  wood 
(coesalpinia  sappan  of  Linn.)  hi  powder,  was  steeped  in 
the  solution,  which  being  afterwards  strained,  was  ap- 
plied as  before  mentioned;  after  which  the  cotton  so 
penciled,  was  exposed  to  the  hottest  sun-shine,  in  order 


264.  Philosophy  of  Permanent  Colours, 

that  the  parts  to  which  the  mordants  had  been  applied, 
might  be  dried  as  much  as  possible;  and  then  the 
cottons  were  thoroughly  soaked  in  large  pits  of  water, 
to  cleanse  them  from  the  loose  superfluous  parts  of  the 
different  mordants,  as  well  as  from  the  buffaloes'  milk, 
&c.;  and  this  being  done,  they  were  slowly  dyed  in 
water  moderately  heated,  with  certain  roots  answering 
nearly  in  their  effects  to  those  of  madder.  Of  these  there 
are  several  sorts  used  for  dyeing  red  in  different  parts 
of  India,  which  will  be  more  particularly  noticed  here- 
after; that  pointed  out  by  the  accounts  in  question,  and 
most  commonly  employed,  is  called  on  the  coasts  of 
Coromandel  and  Malabar  by  the  names  of  chay,  chaia, 
chayaver,  chailliver,  and  raye  dc  chaye.*  And  after 
being  dyed,  the  cottons  underwent  three  different  wash- 
ings with  goats'  dung,  soap,  &c.  and  were  then  bleached 
by  being  exposed  to  the  sun,  and  watered  occasionally, 
to  remove  the  stain  on  the  parts  intended  to  be  left 
white. 

It  appears,  that  in  this  operation  the  buffaloes'  milk, 
and  more  especially  the  astringent  juice  of  the  myro- 
balans,  produced  very  beneficial  and  important  effects, 
by  their  attraction  for  the  aluminous  earth,  which  con- 
tributed greatly  to  decompose  or  separate  it  from  the 

*  This  root  was  supposed,  by  M.  M.  Poivre,  Hellot,  and  others, 
to  be  a  species  of  galium  or  lady's  bed-straw;  afterwards,  however, 
M.  Duhamel  de  Monceau  thought  there  was  sufficient  reason  to 
consider  it  as  the  Hedyolis  herbacea,  Linn.:  lately,  however,  Dr. 
Roxburgh  has  ascertained  it  to  be  a  species  of  oidenlandiay  to  which 
he  has  annexed  the  specific  name  of  umbellata;  (see  Plants  of  Co- 
romandel, vol,  i.  p.  2,  t.  3.)  This  indeed  belongs  to  the  same  class 
and  order  as  the  galium  and  hedyotis  (i.  e.  to  the  tetrand.  monog. 
Linn.);  and  is  called  tsherivello  by  the  Telingas;  che,  saya-ver,  and 
imbourel,  by  the  Tamuls.  Since  my  former  publication  on  this  subr 
ject,  I  have  made  numerous  experiments  with  this  root,  of  which 
an  account  will  be  given  hereafter. 


Pfulosophy  of  Permanent  Colours.  264 

sulphuric  acid,  and  consequently  to  fix  it  more  firmly 
in  the  cotton;  and  being  so  fixed,  it  was  enabled  more 
strongly  to  attract  and  retain  the  colouring  matter  of  the 
chay  root  when  in  the  dyeing  vessel,  and  thereby  to 
produce  a  more  permanent  red  colour  in  the  different 
spots,  figures,  or  designs,  where  the  alum  liquor  had 
been  applied.* 

The  astringent  or  colouring  matter  of  the  myrobalans 
also  contributed  essentially  to  produce  the  purple  and 
violet  stains,  upon  the  parts  or  figures  to  which,  for 
that  purpose,  a  mixture  of  iron  liquor  and  of  the  alu- 
minous mordant  had  been  applied,  as  lately  mentioned; 
the  chay  root  not  having  (as  my  experiments  prove)  the 
property,  like  madder,  of  producing  those  colours  with 
iron. 

After  these  operations,  a  yellonv  composition  was  ap- 
plied by  the  pencil,  &c.  to  the  parts  which  had  been 
preserved  white;  and  when  a  green  was  wanted,  to  other 
parts  which,  with  a  view  to  that  colour,  had  been  dyed 
blue.  This  yellow  composition  was  made  by  dissolving 
powdered  alum  in  a  decoction  of  the  powdered  galls 
of  the  myrobalan  tree,  called  aldecay  by  the  Telingas, 
.&c.  as  just  mentioned.  In  making  this  decoction,  pow- 
dered turmeric  and  dried  pomegranate  rinds  were  some- 
times put  into  the  water,  with  the  aldecay.  But  the  yellow 

*  When  a  solution  of  alum  is  applied  to  calico  which  has  received 
no  impregnation,  it  will  not  be  sensibly  decomposed;  but  on  the 
contrary,  a  great  part  of  it  will  again  crystallize,  so  soon  as  the 
water  which  held  it  in  solution  has  evaporated;  and  none  but  very 
feeble  colours  can  be  raised  upon  such  a  basis.  But  when  calico  has 
been  impregnated  by  such  astringent  and  animal  matters  as  are 
obtained  from  myrobalans  and  buffaloes*  milk,  the  alum  will  not 
only  be  decomposed,  but  the  alumine  will  combine  with  the  astrin- 
gent and  oily  matters  so  obtained,  and  a  basis  will  be  laid  for  a 
colour  almost  as  durable  as  the  Tui-key  red. 

Vol.  I.  2  L 


266  Philosophy  of  Permanent  Colours. 

or  green  resulting  from  this  application,  will  only  endure 
a  few  washings,  before  it  becomes  almost  obliterated. 
Father  Coeurdoux  pretends,  indeed,  that  this  defect  may 
in  a  great  degree  be  obviated  by  mixing  with  the  yellow 
in  question,  some  of  the  astringent  juice  of  the  root  of 
the  plantain  [musa);  but  if  this  had  been  true,  such  mix- 
ture would  doubtless  have  been  employed,  and  in  that 
case  the  yellow  of  the  Indian  chintz  would  not  have  prov- 
ed so  defective,  as  it  is  known  to  have  been  at  all  times. 

In  this  composition  we  have  an  adjective  colour  direct- 
ly combined,  and  topically  applied  with  its  basis,  instead 
of  being  applied  separately,  as  is  most  usual.  Such  com- 
positions {which  will  be  frequently  mentioned  hereafter) 
assume  the  form  of  a  substantive  colour,  without  being 
such  in  reality;  and  as  it  may  be  useful  to  distinguish 
them  by  an  appropriated  term,  I  beg  leave  to  call  them 
pro  substantive  topical  colours^  and  to  apply  that  designa- 
tion wherever  an  adjective  colour,  and  its  basis  or  mor- 
dant, are  thus  mixed  and  applied  together  topically^ 
eitlier  by  the  pencil  or  the  block. 

The  art  of  calico-printing,  since  its  introduction  to 
Europe,  has  been  divested  of  many  tedious  operations 
and  manipulations,  which  indeed  would  have  proved 
insupportably  expensive  here,  on  account  of  the  higher 
price  of  labour,  and  of  almost  every  thing  necessary  to 
human  subsistence.*  But  the  greatest  European  im- 
provement in  this  art,  respects  the  aluminous  mordant, 
and  depends  on  the  employment  of  sugar  of  lead  (ace- 
tite  of  lead),  or  the  oxide  of  that  metal  dissolved  by 

*  Berthollet,  torn  i.  p.  8,  of  his  last  edition,  has  delivered  a  simi- 
lar opinion,  and  he  adds  in  a  note,  "Cette  opinion  est  confirmee 
par  les  details /i/w«  exacts  que  I'on  trouve  dans  Bancroft  Of  Perma- 
nent Colours" — He  co!\siders  the  art  of  dyeing  in  India  as  being 
now  nearly  in  the  state  in  which  it  was  at  the  time  of  Alexander's 
invasion. 


Philosophy  of  Permanent  Colours.  26f 

distilled  vinegar,  and  crystallized;  which  within  the 
memory  of  man  has  been  gradually  brought  into  use, 
without  any  theory,  or  even  suspicion  of  its  true  effect, 
or  of  the  way  in  which  it  has  proved  so  highly  useful. 
This  improved  aluminous  mordant  is  now  generally 
made  by  dissolving  three  pounds  of  alum  in  a  gallon  of 
hot  water;  then  adding  one  pound,  or  in  some  particu- 
lar cases  one  pound  and  a  half,  of  the  acetate  or  sugar 
of  lead,  stirring  the  mixture  well  during  two  or  three 
days,  and  afterwards  adding  to  it  about  two  ounces  of 
potash,  and  as  many  of  clean  powdered  chalk  (carbonate 
of  lime).  In  this  mixture,  both  the  alum  and  the  sugar 
of  lead  are  decomposed  by  a  double  elective  attraction, 
which  produces  two  new  compounds,  according  to  Mr. 
Henry  and  M.  BerthoUet,  because  the  oxide  of  lead 
having  a  stronger  attraction  for  the  sulphuric  acid  than 
for  that  of  the  vinegar,  combines  with  the  former,  and, 
forming  an  insoluble  salt,  subsides  to  the  bottom  of  the 
liquor,  whilst  the  earth  of  alum,  thus  left  in  a  very  di- 
vided state,  unites  to,  and  is  dissolved  by  the  acetic 
acid,  previously  separated  from  the  lead,  and  remaining 
in  the  liquor,  which  thereby  becomes  a  diluted  acetate 
of  alumine;  the  potash  or  chalk  only  serving  to  neu- 
tralize the  excess  of  sulphuric  acid,  which  is  always 
contained  in  alum,  and  which  would  in  some  degree 
hinder  the  alumine  from  being  deposited  and  iixed  in 
the  fibres  of  linen  and  cotton.  But  the  decomposition 
here  described  takes  place  only  in  part,  because  one 
pound  of  sugar  of  lead,  or  even  one  and  a  half,  (the 
greatest  quantity  any  where  proposed,)  is  not  sufficient 
to  decompose  three  pounds  of  alum.  On  the  contrary, 
I  have  found  that  alum  cannot  be  completely  decom- 
posed, without  nearly  its  weight  of  sugar  of  lead:*  and 

*  Having  added  a  pound  of  sugar  of  lead  to  a  pound  of  alum  dis- 
solved in  hot  water,  I  found  that  though  the  alum  was  decomposed 


^6B  Philosophy  of  Permanent  Colours, 

where  less  has  been  used,  I  have  always  been  able,  by 
evaporation,  to  detect  a  quantity  of  it  in  the  aluminous 
mordant.  I  shall  have  occasion  hereafter  to  revert  to 
this  subject,  and  shall  therefore  content  myself  at  pre- 
sent with  remarking,  that  the  printer's  aluminous  mor- 
dant is  not,  in  fact,  a  mere  solution  of  the  alumine,  or 
earth  of  alum,  by  the  acid  of  vinegar,  as  those  eminent 
chemists  Mr.  Henry  and  M.  Berthollet  have  supposed; 
but  that  even  with  the  greatest  proportion  of  sugar  of 
lead  ever  employed  by  the  calico  printers,  it  contains  a 
considerable  portion  of  alum  in  its  original  state;  I  mean 
that  in  which  the  argillaceous  earth  or  alumine  is  com- 
bined with  sulphuric  acid.  But,  notwithstanding  this 
circumstance,  I  shall  generally  consider  this  prepara- 
tion as  being  in  reality,  what  it  is  not  strictly,  an  acetate 
of  alumine;  and  shall  commonly  distinguish  it  either 
by  that  name,  or  by  that  of  the  printer's  aluminous 
mordant. 

The  mixture  or  mordant  in  question  being  thus  made, 
and  the  clear  liquor  decanted  from  the  sediment,  it  is 

and  a  pure  acetate  of  alumine  produced,  yet  the  acetic  acid,  which 
had  dissolved  the  lead,  was  not  sufficient  to  re-dissolve  the  whole 
of  the  alumine,  a  part  of  it  having  subsided  with  the  sulphate  of 
lead;  it  was,  however,  soon  dissolved  by  adding  vinegar  to  it;  and 
this  solution,  when  made  with  strong  vinegar,  proved  as  efficacious 
as  the  pure  acetate  of  alumine  in  lixing  the  colours  of  madder,  &c. 
Gay  Lussac  has  observed  that  an  acetate  of  alumine,  which  when 
cold  is  perfectly  transparent^  becomes  turbid  and  deposits  a  part  of 
its  alumine  when  heated,  and  that  if  left  to  cool  again,  the  alumi- 
nous sediment  will  be  re-dissolved,  and  the  liquor  recover  its  former 
transparency:  an  effect  which  he  thinks  analogous  to  the  coagula- 
tion of  albuminous  matter  by  heat,  of  which  he  has  given  an  expla- 
nation at  p.  197,  of  the  74th  volume  of  the  Annales  de  Chimie.  The 
fact,  however  it  may  be  explained,  enables  us  to  understand  (what 
experience  had  in  some  degree  previously  suggested)  why  the  alu- 
minous basis  sJiould  not  be  applied  ivar?n,  when  it  is  intended  to  be 
copiously  fixed  on  calico,  under  the  operation  of  printing. 


Philosophy  of  Permanent  Colours.  269 

afterwards  thickened  with  flour,*  if  intended  to  be  print- 
ed or  applied  by  the  block  and  with  the  gum  of  the 
mimosa  nilotica  (gum  arabic),  or  of  the  mimosa  Sene- 
gal (gum  of  Senegal),  if  it  be  intended  for  penciling; 
and  being  applied  in  either  of  these  ways  to  linens  or 
cottons,  previously  bleached  and  made  smooth  by  the 
cylinder,  the  latter  are  to  be  thoroughly  driedf  by  a 
stove  heat  of  150  degrees  of  Fahrenheit,  and  afterwards 
put  into  a  copper  partly  filled  with  a  mixture  of  cow 
dung  and  water,  through  which  they  are  to  be  turned 
by  the  winch,  backwards  and  forwards,  until  the  gum 
or  flour  employed  to  thicken  the  mordant  has  been  dis- 
solved, and  the  loose  panicles  of  alumine  separated; 
that  they  may  not  in  the  dyeing  vessel  combine  with  the 

*  Since  my  former  edition,  it  has  been  found  that  by  slightly 
torrefying  the  flour,  it  was  rendered  more  soluble  in  water,  and 
more  suitable  for  the  purpose  of  giving  consistency  to  the  mordant 
in  question;  and  the  brown  colour  which  it  acquires  by  torrefaction 
supersedes  the  use  of  Brasil  wood,  and  other  colouring  matters,  to 
mark  the  parts  which  have  received  the  mordant.  Starch,  by  a  si- 
milar torrefaction,  softens,  swells,  and  emits  a  penetrating  odour; 
and,  the  torrefaction  being  then  stopped,  a  substance  is  obtained, 
which  has  been  lately  much  employed  by  calico-printers  as  a  sub- 
stitute for  the  gum  of  Senegal,  under  the  name  of  British  gum. 

From  half  to  three  quarters  of  a  pound  of  gum  have  commonly 
been  found  necessary  to  each  quart  of  the  mordant,  according-to 
the  season  of  the  year,  and  the  sort  of  figures  or  impressions  in- 
tended to  be  made.  So  much  consistency  should  be  always  given 
to  the  liquor  as  will  hinder  it  from  spreading  beyond  its  proper 
limits,  taking  care  at  the  same  time,  that  it  shall  retain  so  much 
jiuidity,  as  thoroughly  to  penetrate  the  fibres  of  the  calico,  and,  in 
the  language  of  the  printers,  serve  as  a  leader  or  conductor  to  the 
alumine,  &c. 

t  This  thorough  desiccation,  by  artificial  heat,  contributes  very 
much  towards  a  more  fierfect  union  of  the  aluminous  and  ferrugi- 
nous bases  with  the  fibres  of  the  cotton^  by  causing  an  evaporation 
of  the  acetic  acid,  and  also  of  the  water,  which  by  their  affinities, 
would  obstruct  the  desired  union. 


^70  Philosophy  of  Permanent  Colours. 

colouring  matter ,  and  discolour  the  grounds  intended  to 
be  preserved  white.  The  cow  dung  in  this  operation 
was  supposed  to  be  useful  only  by  combining  with, 
and  entangling  the  superfluous  parts  of  the  mordant,  so 
as  to  hinder  them  when  separated  from  the  figures  to 
which  they  had  been  first  applied,  from  attaching  them- 
selves improperly  to  other  parts,  and  becoming  the  basis 
of  an  unpleasant  stain.  But  there  is  reason  to  believe 
that  cow  dung,  by  the  gastric  juices,  gelatine  and  albu- 
men, which  it  contains,  aftbrds  a  very  beneficial  im- 
pregnation to  the  printed  calico,  of  some  animal  matter, 
which  combining  with  the  mordant,  serves  to  bind  it 
more  strongly  to  be  printed  calico,  and  afterwards  to 
increase  its  attraction  for  the  colouring  matter,  like  some 
of  the  animal  impregnations  which  are  so  necessary  for 
the  Turkey  red.* 

*  Mr.  Watt  has  supposed  that  the  animal  gall  contained  in  cow- 
dung,  exeixises  a  particular  power  in  this  operation,  of  separating 
the  acetic  acid  from  the  aluniine,  and  that  by  combining  with  the 
latter,  it  renders  it  more  efficacious  afterwards,  in  attracting  and 
holding  the  colouring  matter  in  combination.  Mr.  Widmer,  of  Jouy, 
near  Versailles,  has  entertained  nearly  a  similar  opinion,  (as  Ber- 
thollet  reports);  he  believing  that,  "  dans  le  bouzage  il  se  forme 
line  combinaison  triple  de  la  matiere  animalc  avec  Talumine  et  la 
loile,  qui  ajoute  a  la  beaute  des  couleurs:*'  and  for  this  opinion, 
BerthoUet  thinks  there  is  some  foundation,  because  water  alone 
does  not  answer  the  purpose;  and  he  adds,  that  an  examination,  not 
indeed  the  most  minute^  of  cow  dung,  did  not  enable  him  to  discover 
in  it  any  thing  likely  to  produce  these  beneficial  effects,  excepting 
a  matter  analogous  to  bile,  "une  matiere  analogue  a  la  bile."  Ele- 
mens,  8cc.  tom.  i.  p.  90. 

Haussman  substituted  powdered  chalk  for  cow  dung  (with  water); 
but  found  the  colours  which  were  raised  afterwards  upon  the  alu- 
minous basis  to  be  very  feeble,  though  those  upon  the  oxide  of  iron, 
which  had  at  the  same  time  been  subjected  to  the  action  of  chalk 
and  water,  did  not  appear  greatly  defective.  Soap  and  w^ater  being 
employed  instead  of  cow  dung  and  water,  produced  effects  more 
hurtful  to  the  aluminous  basis  than  those  of  chalk  and  water.  If 


Philosophy  of  Permanent  Colours.  271 

Subsequently  to  this  dunging  operation,  the  pieces  of 
ealico  are  to  be  well  rinced,  and  beat  in  clean  running 
water,  to  remove  as  far  as  possible  every  loose  particle 
of  the  mordant,  which  might  otherwise,  when  in  the 
dyeing  vessel,  occasion  an  improper  stain. 

By  thus  substituting  the  acetic  for  the  sulphuric  acid, 
in  the  aluminous  mordant  lately  described,  several  con- 
siderable advantages  are  gained.  The  acetate  of  alumine 
being  much  more  soluble  in  water  than  common  alum, 
the  liquor  will  contain  a  much  larger  proportion  of  alu- 
mine, than  could  be  otherwise  suspended  in  it;  and  with 
this  advantage,  moreover,  that  it  will  not  be  liable  to 
form  crystals  in  or  upon  the  linens  or  cottons  in  drying, 
as  would  happen  with  a  solution  of  common  alum,  the 
acetate  of  alumine  being  incapable  of  crystallization.  I 
may  add  also,  that  the  acid  of  vinegar  being  volatile, 
and  having  a  much  weaker  attraction  for  its  earthy  basis 
than  the  sulphuric  acid  has,  the  former  will  be  speedily 
separated  and  carried  off,  especially  by  the  heat  of  the 
stoves  employed  for  drying  the  pieces  printed  with  it, 
and  will  leave  behind  the  alumine  which  it  had  dissolved, 
and  which,  being  no  longer  encumbered  by  any  other 
attraction,  will  yield  itself  wholly  to  that,  which  subsists 
between  it  and  the  fibres  of  linen  or  cotton,  and  will 
unite  with  them  more  copiously  and  firmly  than  it  other- 
wise could  do,  and  be  thereby  enabled  more  strongly  to 
attract  and  fix  the  colouring  matters  in  the  dyeing  ves- 
sel. This,  however,  will  only  prove  true,  so  far  as  the 
sulphate  of  alumine  has  been  really  decomposed  by  the 
acetate  of  lead,  or  so  fiir  as  the  alumine  has  been  com- 
bined with  the  acetic  instead  of  the  sulphuric  acid.* 

cow  dung  were  only  useful  by  tidckening  the  water,  oatmeal,  or  the 
meal  of  lint-seed  might  well  supply  its  place;  but  I  have  not  found 
them  capable  of  doing  so. 

*  Since  these  observations  were  first  published,  cheaper  means 


272  Philosophy  of  Permanent  Colours* 

As  the  practice  of  calico  printing  has  been  but  lately 
introduced  into  Europe,  and  as  the  acetated  aluminous 
mordant  does  not  appear  to  have  been  previously  known 
in  any  other  country,  we  might  have  expected  that  its 
discovery  in  this^  would  have  been  deemed  a  matter  so 
important,  as  to  have  constituted  an  aera  in  the  history 
of  the  art;  and,  therefore,  I  was  not  a  little  surprised  in 
finding  that  no  writer  had  mentioned,  and  that  no  calico- 
printer,  of  whom  I  have  inquired,  could  inform  me,  at 
what  time,  or  by  whom,  this  mordant  was  first  employ- 
ed, as  the  basis  of  red  and  yellow  colours  in  calico-print- 
ing. My  wonder  has,  however,  ceased  on  this  subject, 
since  I  have  inspected  a  considerable  number  of  recipes 
for  making  the  several  mixtures  employed  as  mordants, 

have  been  discovered  of  forming  an  acetate  of  alumine.  White  lead, 
not  adulterated  by  carbonate  of  lime,  being  dissolved  in  strong  vine- 
gar, was  found,  in  several  experiments  which  I  made,  to  answer  the 
purpose  of  sugar  of  lead,  and  to  produce  a  good  aluminous  mordant, 
by  adding  to  the  solution  a  suitable  proportion  of  powdered  alum; 
and  I  afterwards  found  that  litharge  dissolved  in  vinegar,  instead  of 
white  lead,  was  equally  useful  for  decomposing  alum.  But  soon 
after  it  had  been  ascertained,  that  the  acid  obtained  from  oak,  beech, 
and  other  woods,  by  converting  them  to  charcoal  in  close  vesselsy 
and  collecting  the  acid  by  proper  tubes  and  receivers,  was  truely  an 
acetic  acid  with  only  an  intermixture  of  an  empyreumatic  oil,  and 
perhaps  a  little  ammonia,  this  pyroligneous  acid  was  generally  sub- 
stituted for  vinegar,  and  employed  to  dissolve  the  oxide  or  carbonate 
of  lea,d;  and  the  solution  so  made,  was,  with  a  considerable  diminu- 
tion of  expense,  employed  to  decompose  alum,  instead  of  sugar  of 
lead;  the  empyreumatic  oil,  excepting  its  unpleasant  smell,  doing 
little  or  no  harm  even  to  the  most  lively  and  delicate  colours,  and 
proving  in  some  degt  ee  beneficial  to  those  depending  on  a  ferrugi- 
nous basis. 

More  recently,  however,  it  has  been  discovered,  that  by  dissolv-* 
ing  lime  instead  of  an  oxide  or  carbonate  of  lead,  in  the  pyroligneous 
or  other  acetic  acid,  alum  might  be  still  more  cheaply  decomposed; 
and  at  present,  an  acetate  of  lime  is,  I  believe,  generally  employed, 
instead  of  the  acetate  of  lead,  to  produce  the  aluminous  mordant. 


Philosophy  oj* Permanent  Colours*  273 

soon  after  the  business  of  calico-printing  began  to  be 
carried  on  with  some  degree  of  success  here,  and  in 
other  parts  of  Europe.  In  one  of  these,  which  seems  to 
have  been  the  earliest,  alum,  sal  ammoniac,  saltpetre, 
red  orpiment,  and  kelp,  were  directed  to  be  mixed  with 
water.  In  another,  which  probably  followed  this,  it  was 
directed  that  these  ingredients  should  be  dissolved  in 
vinegar.  In  a  succeeding  recipe,  a  little  sugar  of  lead 
was  directed  to  be  employed,  but  in  a  quantity  too 
small  to  be  of  any  considerable  use;  I  mean  one  ounce 
of  it  for  every  pound  of  alum.  Afterwards,  the  calico- 
printers,  without  any  system  or  reasonable  motive,  ap- 
pear in  different  instances  to  have  added  verdigrise, 
arsenic,  corrosive  sublimate,  blue  vitriol,  litharge,  and 
white  lead.  By  stumbling  upon  the  two  last  (which  alone 
were  of  any  use),  it  happened,  where  vinegar  had  been 
also  employed,  as  it  commonly  was  in  some  shape,  that 
after  a  variety  of  decompositions  and  recompositions, 
some  portion  of  acetate  of  alumine  was  formed,  the  good 
effects  of  which  were  experienced,  though  without  any 
true  knowledge  of  the  ways  and  means  by  which  they 
had  been  produced.  By  degrees,  however,  the  printers 
seem  to  have  increased  the  quantity  of  sugar  of  lead, 
and  several  of  them  to  have  suspected  that  many  of  the 
other  ingredients  usually  employed  for  making  their 
mordants  were  useless.  Some  of  them,  therefore,  began  to 
omit  one,  and  some  another  of  these  ingredients,  until  at 
length  all  the  useless  ones  were  laid  aside,  though  with- 
out the  aid  of  any  chemical  reasoning  on  the  subject, 
and  without  any  one  having  ever  suspected,  as  indeed 
few  of  them  do  at  this  day,  that  the  lead  which  they 
continued  to  employ,  occasioned  any  decomposition 
of  the  alum,  or  tliat  the  mordant  so  produced  did  not 
really  contain  all  the  lead  and  other  ingredients  used  to 
prepare  it.  Among  the  useless  ingredients  before  men- 
VoL.  I.  2M 


^74  Philosophy  of  Pennatient  Colours, 

tioned,  corrosive  sublimate  seems  to  have  been  retained 
the  longest,  since  Mr.  Wilson  includes  it  in  his  recipe, 
which  was  published  so  lately  as  the  year  1786.  (See 
his  Essiiy  o.i   Light  and  Colours,  Sec.) 

It  is  not  wonderful,  therefore,  that  no  particular  per- 
son or  period  has  been  noted,  or  remembered,  as  dis- 
tinguishable for  the  first  invention  of  the  acetated  alumi- 
nous mordant;  since  the  sugar  of  lead,  or  other  means 
of  forming  it,  were  at  first  used  by  chance  so  sparingly, 
as  to  have  scarcely  produced  any  better  effect  than  would 
have  resulted  from  the  mere  solution  of  alum,  and  the 
alterations  and  improvements  by  which  the  mordant 
afterwards  acquired  its  present  form,  I  had  almost  said 
perfection,  were  made  by  such  imperceptible  grada- 
tions, and  resulted  so  much  from  the  random  additions 
and  omissions  of  different  individuals,  (no  one  of  whom 
seems  to  have  been  guided  by  any  thing  approaching 
to  a  just  theory,)  that  neither  the  discovery,  nor  any 
considerable  step  towards  it,  can  properly  be  referred 
to  any  one  person  or  period. 

Mr.  Henry,  justly  sensible  of  the  superior  advantages 
of  the  acetated  aluminous  mordant  in  calico-printing, 
and  conceiving  it  to  have  really  been  very  anciently 
known  and  employed  in  those  countries  where  the  art 
was  first  practised,  concludes  from  thence,  that  it  must 
have  resulted  from  a  very  advanced  state  of  chemical 
knowledge  in  those  countries,  at  some  very  remote  pe- 
riod, which  was  afterwards  lost,  whilst  the  improve- 
ments arising  from  it  in  this  respect  continued  to  be 
practised  and  handed  down,  through  a  long  succession 
of  ages  to  the  present  time.  ''  To  have  invented  (says 
he)  the  process  of  printing,  in  the  manner  described  by 
Pliny,  the  inhabitants  of  India  must  probably  have 
known  how  to  prepare  alum:  they  must  have  been 
acquainted  with  the  manner  of  dissolving  lead  in  the 


Philosophy  of  Permanent  Colours,  275 

vegetable  acids;  they  must  at  least  have  been  acquainted 
with  the  component  parts  of  these  salts,  and  they  must 
have  had  a  knowledge  of  double  elective  attractions, 
&c."  In  truth,  however,  the  inhabitants  of  India  neither 
had,  nor  have  they  at  present,  any  knowledge  of  the 
use  of  sugar  of  lead,  or  of  any  other  preparation  of  that 
metal  which  could  produce  similar  effects  in  calico-print- 
ing; a  solution  of  common  alum  in  water  being  their 
only  aluminous  mordant,  and  the  previous  application 
of  the  soluble  parts  of  myrobalans  and  of  buffaloes'  milk, 
to  their  calicoes,  aided  by  a  very  hot  sun-shine,  and  the 
complete  desiccation  which  it  produces,  enabling  them, 
without  any  thing  like  an  acetate  of  alumine,  to  give  equal 
durability  to  their  colours.  This  fact  I  have  learned,  not 
only  from  all  the  accounts  published,  or  transmitted  to 
Europe  respecting  this  point,  but  from  the  positive  ver- 
bal informations  of  eye  witnesses  to  the  practice  of  calico- 
printing  in  that  part  of  the  world,  and  particularly  of  a 
gentleman  of  great  veracity,  as  well  as  knowledge  on 
this  subject,  who  formerly  carried  on  the  business  of 
calico-printing  very  extensively  in  Bengal  (principally 
for  account  of  the  East- India  Company):  and  indeed 
sugar  of  lead  is  so  far  from  being  used  for  this  purpose 
there,  that  within  a  few  weeks  I  have  received  a  letter 
from  Mr.  John  Adie,  (successor  to  the  gentleman  last 
mentioned,)  dated,  *'  Gondelpara,  near  Chandernagore, 
the  10th  of  February,  1792,"  and  mentioning,  that  he 
had  some  little  time  before  been  obliged  to  pay  twenty 
shillings  the  pound  for  sugar  of  lead,  in  order  to  prepare 
a  particular  colour  which  I  had  formerly  recommended; 
so  far  was  this  ingredient  from  being  in  use  there  for  any 
such  purpose. 

We  may,  therefore,  safely  conclude,  that  the  forma- 
tion of  an  acetate  of  alumine,  and  its  application  as  a 
mordant  in  calico-printing,  was  not  an  oriental  disco- 


276  Philosophy  of  Permanent  Colours. 

very;  and  that  it  did  not  result  from  any  knowledge  of 
double  elective  attractions,  or  any  other  extensive  che- 
mical knowledge,  either  in  ancient  or  modern  times; 
since  those  who  gradually  stumbled  upon  and  intro- 
duced the  use  of  it,  were  totally  ignorant  of  the  decom- 
positions and  recompositions  which  took  place  in  their 
mixtures,  and  always  supposed,  as  all  other  calico- 
printers  have  till  lately  done,  and  as  most  of  them  now 
do,  that  the  aluminous  mordatit  really  consisted  of  every 
thing  used  in  producing  it. 

To  illustrate  more  plainly  the  differences  of  colouring 
matter,  as  well  as  the  action  of  an  aluminous  basis  upon 
them,  let  us  examine  its  effects  in  a  few  particular  in- 
stances: taking  a  small  piece  of  calico,  upon  which  cer- 
tain figures  and  designs  had  been  printed  with  the  ace- 
tated  aluminous  mordant,  and  which,  after  being  dried, 
had  been  cleansed  in  the  usual  way,  I  dyed  it  in  water 
with  saffron;*  the  water  readily  extracted  the  yellow 
i^olour  of  the  saffron,  and  the  calico  soon  imbibed  so 
much  of  the  colour,  as  to  become  equally  yellow  in  all 
its  parts,  without  any  difference  of  shade,  even  where 
the  alumine  had  been  applied.  The  calico  so  coloured 
being  exposed  to  air,  soon  became  equally  and  uni- 
formly white;  the  colouring  matter  of  the  saffron  having 
no  affinity  to  the  alumine:  to  see,  however,  whether  this 
last  remained  fixed  in  the  fibres  of  the  cotton,  I  dyed 
the  same  piece  which  the  safiron  colour  had  thus  aban- 
doned, in  water  with  a  little  Brasil  wood,  and  the  figures, 
where  the  alumine  had  been  applied,  became  of  a  strong, 
full,  and  beautiful  crimson;  the  other  parts,  to  which  no 

*  The  colouring  matter  of  saffron  readily  dissolves  in  water,  but 
is  soon  destroyed  by  the  rays  of  the  sun;  it  gives  a  rich  yellow  to 
linen,  cotton,  &c.  but  having  no  affinity  for  any  known  basis,  it  has 
no  permanency,  though  it  will  acquire  blueish  and  greenish  shades, 
when  acted  upon  by  the  sulphuric  and  nitrid  acids. 


Philosophy  of  Permanent  Colours.  277 

basis  had  been  applied,  being  but  slightly  discoloured. 
The  calico  so  dyed,  being  exposed  to  the  sun  and  air 
two  or  three  days,  the  spaces  to  which  no  mordant  had 
been  applied  became  perfectly  white;  and  the  figures 
impregnated  with  alumine  had  lost  some  of  their  fine 
crimson  colour,  which  gradually  diminishing,  by  a  con- 
tinued exposure,  was  all  gone  at  the  end  of  eight  days. 
In  this  instance,  the  aluminous  basis  had  a  certain  affinity 
with  the  colouring  matter  of  the  Brasil  w^ood,  (which  was 
not  the  case  with  that  of  saffron,)  but  not  so  much  as  to 
fix  and  retain  it  permanently.  To  ascertain,  however,  that 
the  defect  arose  from  the  want  of  a  sufficient  affinity  be- 
tween the  colouring  matter  and  the  alumine,  and  not 
between  this  last  and  the  cotton,  I  took  the  same  calico, 
which  had  been  already  twice  dyed,  and  dyed  it  a  third 
time  in  water  with  madder,  whereby  the  whole  became 
coloured,  but  the  figures  impregnated  with  alumine 
much  more  deeply  than  the  other  parts;  a  proof  that  the 
alumine  still  remained  fixed,  notw^ithstanding  the  escape 
of  the  Brasil  wood  crimson,  and  that  it  had  again  entered 
into  a  triple  combination  with  the  madder  colour,  and 
the  fibres  of  the  cotton.  The  piece  so  dyed,  being  well 
boiled  in  water  soured  w^ith  bran,  and  exposed  to  sun- 
shine and  air,  in  a  few  days  became  white  in  the  parts 
where  no  mordant  had  been  applied  to  fix  and  retain  the 
colour,  whilst  the  figures  formed  by  the  application  of 
alumine,  retained  all  their  body  and  brightness;  the 
colouring  matter  of  the  madder,  in  this  triple  combina- 
tioU;  not  being  liable  to  destruction  or  separation  by  the 
same  means  which  destroyed  or  separated  it  where  no 
such  bond  of  union  or  means  of  preservation  existed.* 

*  M.  Berthollet,  in  the  last  edition  of  his  Elements,  8cc.  (torn.  i. 
p.  80)  has  introduced  my  account  of  these  experiments,  to  illus- 
trate and  prove  the  affinities  of  alumine  employed  as  a  basis,  and 


278  Philosophy  of  Permanent  Colours. 

It  has  been  already  noticed,  that  in  oriental  calico- 
printing  the  solution  of  alum  is  coloured  red  with  samp- 
fan  or  sappan  wood;  and  I  might  have  added,  that  in 
dyeing  with  chay  root,  the  red  colour  of  the  wood  is 
dislodged  from  the  pores  of  cotton  by  the  superior  at- 
traction of  the  root  colour,  which  takes  its  place.  Nei- 
ther the  East  Indians,  however,  nor  ihe  writers  who 
have  given  accounts  of  their  operations,  seem  to  have 
been  apprised  of  this  fact;  but  have  concluded  that  the 
red  wood  colour  was  fixed,  and  made  durable  by  apply- 
ing that  of  the  chay  root.*  To  ascertain  the  truth  on  this 
point,  I  made  several  experiments,  of  which  an  account 
was  given  in  my  former  edition;  but  they  are  now  omit- 
ted,  because  those  which  I  have  since  made  with  the 
chay  root  itself  and  which  will  be  stated  hereafter,  must 
render  the  former  unnecessary. 

After  this  account  of  the  acetate  of  alumine,  it  is  pro- 
per that  I  should  notice  that  of  iron,  commonly  called 
iron  liquor,  which,  as  employed  in  Europe,  was  mani- 
festly borrowed  from  the  Indians,  with  only  the  substi- 
tution of  a  vinegar  from  wine  or  malt,  for  that  obtained 
by  fermenting  the  juice  of  some  of  the  different  species 
of  palm  trees. 

also  the  different  dispositions  of  colouring  matters  to  be  acted  upon 
by  these  affinities. 

*  This  erroneous  opinion  has  been  again  very  lately  propagated 
in  a  French  periodical  work,  of  considerable  respectability,  ("  An- 
nales  des  Arts  et  Manufactures,"  No.  51,)  where  M.  Le  Goux  de 
Flaix,  in  giving  an  account  of  the  chay  root,  says,  "  This  root  is 
useful  not  to  give  colour,  but  only  to  fix  that  which  has  been  other- 
wise given;"  and  he  adds,  that  by  not  knowing  this  fact,  it  was  found 
impossible  to  make  any  use  of  a  large  quantity  of  the  chay  root, 
imported  by  the  French  East  India  Company  to  France,  in  the  year 
1774.  The  true  cause,  however,  of  the  failure  here  mentioned,  will 
be  explained  hereafter,  when  I  shall  have  occasion  to  notice  a  si- 
milar failure,  in  regard  to  a  recent  importation  into  this  country,  by 
the  English  India  Company. 


Philosophy  of  Permanent  Colours,  279 

The  means  of  producing  an  acetate  of  ircm,  obviously 
presented  themselves,  and  did  not  require  any  more 
chemical  knowledge,  than  people  but  very  moderately 
civilized  are  commonly  found  to  possess.  Iron,  in  a  state 
proper  for  being  dissolved  by  vinegar,  might  be  pro- 
cured, without  a  previous  decomposition  for  that  parti- 
cular purpose.  But  this  was  not  the  case  with  alumine, 
of  which  the  nature  was  completely  unknown,  as  well 
as  the  ways  of  procuring  it;  and  even  at  this  time,  though 
we  know  it  to  be  a  particular  and  pure  species  of  clay, 
we  do  not  find  it  either  practicable,  or  advantageous,  to 
obtain  it,  except  by  separating  it  from  the  sulphuric 
acid,  with  which  it  has  been  previously  dissolved,  and 
combined  in  common  alum. 

The  first  European  calico-printers,  in  making  their 
iron  liquor,  employed  many  useless  ingredients,  as  they 
also  did  in  making  the  aluminous  mordant.  In  the  more 
early  prescriptions  I  have  found,  besides  old  iron,  and 
vinegar  or  sour  beer,  verdigrise,  sugar  of  lead,  blue  vi- 
triol, antimony,  urine,  the  brine  of  pickled  herrings,  salt- 
petre, sal  ammoniac,  and  other  ificongruous  matters,  fre- 
quently directed;  and  they  were  thought  to  be  useful, 
because  they  did  not  hinder  the  oxide  of  iron  from  per- 
forming its  office  as  a  basis.  Rye  meal  was  for  many 
years  very  commonly  employed,  and  probably  with 
some  advantage.  Afterwards,  however,  experience,  di- 
rected by  the  light  of  chemistry,  enabled  the  manufac- 
turers and  consumers  of  this  mordant,  gradually  to 
discard  the  useless  ingredients  employed  in  making  it, 
as  they  also  did  those  which  had  for  a  considerable  time 
encumbered,  and  in  some  degree  injured  the  mordant, 
from  alum.  Iron  alone,  dissolved  by  an  acetous  acid, 
then  constituted  the  iron  liquor;  and  to  produce  this 
acid,  malt,  or  sour  beer,  or  the  washings  of  sugar  hogs- 
heads, were  commonly  employed,  as  being  the  most 


280  Philosophy  of  Permanent  Colours. 

economical;  and  broken  iron  hoops,  or  other  thin  pieces 
of  old  iron,  were  subjected  to  the  slaw  action  of  the 
acid.  And  when  a  more  concentrated  solution  was 
wanted,  either  as  the  basis  of  very  full  adjective  co- 
lours, or  as  a  substantive  topical  colour,  certain  pro- 
portions of  sulphate  of  iron  were  dissolved  in  the  iron 
liquor,  which,  with  or  without  this  addition,  always  re- 
quired to  be  thickened,  like  the  aluminous  mordant, 
when  topically  applied  by  the  pencil,  or  printed  by  en- 
graved blocks. 

I  scarcely  need  to  add,  that  since  the  nature  of  pyro- 
ligneous  acid  was  ascertained,  this  last  has  been  pre- 
ferred, as  the  cheapest,  and  in  some  respects  most  use- 
ful, for  making  the  acetate  of  iron,  as  well  as  that  af 
alumine. 

When  pieces  of  calico  have  been  printed  with  iron 
liquor,  whether  it  be  applied  to  those  which  either  have 
received,  or  are  intended  to  receive,  the  aluminous 
mordant  also,  they  are  to  be  thoroughly  dried  by  a 
stove  heat,  and  afterwards  passed  through  the  mixture 
of  cow-dung  and  warm  water,  in  the  manner  directed 
for  pieces  which  have  been  printed  with  the  acetate  of 
alumine  only,  and  with  a  view  to  similar  effects;  and 
they  are  afterwards,  in  the  language  of  the  calico- 
printers,  to  be  streamed^  or  extended,  in  running  water, 
and  beat,  to  remove  all  the  loose  or  uncombined  parti- 
cles of  the  mordant,  and  thus  fit  them  to  be  dyed,  with 
either  madder,  sumach,  weld,  or  quercitron  bark;  these 
being  the  principal,  and  almost  the  only  adjective  co- 
louring matters  so  employed  by  calico-printers,  and 
sufficient  (excepting  the  blue  from  indigo)  to  produce, 
with  the  aluminous  and  ferruginous  mordants,  all  the 
various  colours  seen  and  admired  on  printed  calico. 

E.  G.  If  pieces  of  calico,  to  which  these  mordants 
have  been  applied  both  separately  and  mixed,  be  put 


Fhilosophy  of  Permanent  Colours,  281 

into  a  dyeing  vessel,  with  water  scarcely  blood- warm, 
and  in  which  three,  four,  or  five  pounds  of  madder  in 
powder,  for  each  piece,  have  been  previously  mixed, 
and  they  be  turned,  as  usual,  through  the  liquor,  by 
the  winch;  gradually,  but  slowly,  raising  the  heat,  so 
that  it  may  only  reach  the  boiling  point  at  the  time 
when  the  calicoes  will  have  been  sufficiently  dyed,  the 
several  pieces  will  be  found  to  have  imbibed  colour  in 
every  part.  The  figures  or  places  to  which  the  unmixed 
iron  liquor  was  applied,  will  have  been  dyed  black,  and 
those  on  which  the  aluminous  mordant  was  printed, 
will  be  red,  of  different  shades,  if  the  mordant  had  been 
used  at  different  degrees  of  concentration;  and,  if  both 
mordants  were  mixed  and  applied  in  different  propor- 
tions, such  applications  will  have  produced  various 
shades  of  purple,  violet,  chocolate,  and  lilac  colours; 
whilst  the  parts,  or  grounds^  intended  to  be  ultimately- 
left  white,  will  manifest  a  considerable  brownish  red 
discoloration:  but  as  the  madder  colour  producing  it, 
is  not  then  united  to  the  calico,  by  the  affinity  or  attrac- 
tion of  any  intermediate  basis,  it  will  not  be  able,  as  in 
other  parts ^  to  resist  the  action  of  exterior  agents,  and 
may  therefore  (as  is  usually  done),  be  removed,  and  the 
grounds  made  white ^  by  boiling  the  pieces  in  water 
soured  by  fermented  bran,  and  by  afterwards  spreading 
them  for  some  days  (according  to  the  season)  upon  the 
grass;  where,  with  the  well  known  treatment,  the  co- 
lours dyed  upon  a  basis  will  become  brighter,  whilst 
that  without  one  will  completely  disappear. 

Calico,  printed  with  the  same  mordants,  and  dyed 
with  the  quercitron  bark,  (quercus  tinctoria,  orquercus 
nigra,  Linn.),  will  acquire  fixed  and  bright  yellows  of 
different  shades,  upon  the  aluminous  basis,  and  various 
drab  colours  upon  that  of  iron.  A  mixture  of  these 
bases  will  produce  olive  colours.  Along  with  these  it  is 

Vol.  L  2  N 


282  Philosophy  of  Permanent  Colours. 

usual  to  produce  black  impressions  at  the  same  time, 
by  previously  applying  to  the  calico  a  mordant  com- 
posed of  iron  liquor  and  galls;  by  which  figures,  which, 
without  the  galls,  would  only  have  manifested  a  dark 
drab  colour,  are  made  blacky  by  dyeing  with  the  quer- 
citron bark;  and  if  the  dyeing  be  conducted  as  I  shall 
hereafter  direct,  the  grounds  will  be  so  little  discolour- 
ed, that  no  exposure  upon  the  grass  will  be  required,  as 
is  necessary  with  madder  and  weld;  an  advantage  which 
has  nearly  put  an  end  to  the  use  of  weld  in  calico- 
printing. 

This  method,  however,  of  dyeing  yellow  upon  a  basis, 
is  an  European  invention;  the  people  of  India  having  only 
given  it,  as  already  mentioned,  by  a  pro-substantive  mix- 
ture of  the  decoction  of  the  galls  of  myrobalans  with 
alum.  And,  indeed,  this  practice  was  followed  here  for 
some  time  after  the  introduction  of  the  art  into  Europe, 
excepting  that,  instead  of  the  galls  of  the  myrobalan 
tree,  a  decoction  of  French  berries  (rhamnus  infccto- 
rius,  Linn.)  was  employed;  by  which,  indeed,  a  very 
full  bright  yellow  was  at  first  communicated,  but  of  so 
fugitive  a  nature,  that  the  use  of  these  berries,  which  in 
some  degree  still  subsists,  ought  to  be  discouraged;  it 
being  impossible,  by  any  means  yet  known,  to  obtain 
from  them  a  colour  fit  for  any  other  purpose  than  that 
of  deception. 

Hitherto,  the  art  of  calico-printing  has  been  confined 
almost  solely  to  linens  and  cottons,  which  are  suited  to 
it,  by  being  susceptible  of  a  permanent  union  with  co- 
louring matters,  and  especially  with  their  bases,  by  only 
the  common  warmth  of  the  atmosphere:  and  as  this  is 
also  the  case  of  silk,  there  can  be  no  doubt  but  this  last 
might  be  made  the  subject  of  new  and  beautiful  embel- 
lishments in  that  way,  which,  if  properly  executed, 
would  undoubtedly  become  a  source  of  gratification  to 
the  public,  and  of  profit  to  individuals. 


Philosophy  of  Permanent  Colours,  283 

Very  lately  indeed  a  species  of  topical  dyeing  or  stain- 
ing, very  much  resembling  some  parts  of  calico-printing, 
has  been  ingeniously  applied  to  woollen  stuffs,  and  par- 
ticularly those  called  kerseymeres,  for  waistcoat  patterns, 
&c.  What  I  mentioned  in  a  former  chapter,  of  the  ne- 
cessity of  a  considerable  degree  of  heat,  to  enable  the 
fibres  of  wool  to  receive  and  combine  with  colouring 
matters,  will  afford  some  idea  of  the  difficulty  of  apply- 
ing and  fixing  different  colours  in  the  form  of  spots  or 
figures  upon  woollen  stuffs  in  this  way  by  dyeing;  the 
particular  mode  and  means  by  which  this  difficulty  is 
overcome,  and  the  several  colours  fixed  in  the  fibres  of 
wool,  are  still  kept  secret  as  much  as  possible.  How 
proper  colours  for  this  purpose  may  be  provided,  either 
from  substantive  colouring  mattt  rs,  or  from  the  adjective 
ones,  made  into  the  form  of  a  strong  decoction,  and 
mixed  with  the  proper  mordants,  (as  in  the  instance 
which  I  lately  noticed  of  a  pro- substantive  yellow,)  will 
be  easily  understood  by  those  who  may  attend  to  what 
has  been,  or  will  be,  explained  in  the  course  of  this 
work;  and  such  colours  being  so  prepared,  and  printed 
upon  kerseymere,  Sec.  in  the  usual  ways,  may  be,  as  I 
have  found  on  trial,  and  as  I  am  informed  they  are, 
made  to  penetrate  and  unite  with  the  wool,  by  placing 
the  stuff  so  printed  in  the  steam  of  boiling  water  for  a 
sufficient  length  of  time,  first  wrapping  it  up  in  thick 
paper,  doubled  or  trebled,  so  as  to  exclude  the  moisture, 
so  far  at  least  as  that  it  may  not  occasion  the  colours  to 
run  beyond  their  proper  limits. 

After  this  summary  account  of  the  origin,  progress, 
and  nature  of  calico-printing,  intended  to  illustrate  more 
distinctly  the  effects  of  the  principal  bases  or  mordants, 
it  will  be  proper  here  to  take  a  general  view  of  the  facts 
which  respect  the  application  of  these  bases,  for  fixing 
and  modifying  different  adjective  colours,  not  by  topical, 


284  Philosophy  of  Permanent  Colours. 

but  by  general  dyeing,  as  well  upon  wool  and  silk,  as 
on  linen  and  cotton. 

The  two  last  of  these,  spun  into  thread  or  yarn,  and 
either  woven  or  not,  are  made  fit  for  the  application  of 
a  basis,  by  being  boiled,  for  the  space  of  three  or  four 
hours,  in  a  solution  or  lye  of  potash  or  of  soda,  of  suit- 
able  strength;  then  spread  for  some  time  on  the  bleach- 
ing-ground;  afterwards  soaked  in  water,  made  sour  by 
the  addition  of  one-fiftieth,  or  sixtieth,  of  its  weight  of 
sulphuric  acid,  or  oil  of  vitriol;  and  finally  rinced  tho- 
roughly in  clean  water,  and  dried.  When  thus  prepared, 
if  the  aluminous  basis  is  intended  to  be  applied  to  them, 
perhaps  there  is  no  form  in  which  it  could  be  more 
effectual  than  that  of  the  acetated  aluminous  mordant, 
though  motives  of  economy  have  always  induced  the 
mere  dyers  of  linen  and  cotton  to  employ  cheaper  pre- 
parations of  that  basis.  The  sulphate  of  alumine,  or 
common  alum,  will  indeed  yield  a  part  of  its  earthy 
basis  to  linen  and  cotton,  when  dissolved  by  water  and 
applied  to  them;  but  it  does  this  more  readily  when  de- 
prived of  its  excess  of  acid  by  potash  or  calcareous 
earth;  and  it  is  in  this  way  commonly  employed  as  a 
mordant  for  linens  and  cottons.  About  four  ounces  of 
alum,  with  water  sufficient  to  dissolve  it,  and  half  an 
ounce,  or  somewhat  less,  of  potash,  are  commonly  al- 
lowed for  each  pound  of  linen  or  cotton  intended  to  be 
dyed;  and  the  latter  are  to  be  macerated,  &c.  in  this 
liquor,  cold,  or  only  blood-warm,  until  thoroughly  and 
equally  penetrated  by  it,  and  afterwards  well  rinced,  to 
separate  the  superfluous  or  loosely  adhering  alum,  &c.* 

*  If,  instead  of  the  small  proportion  of  potash  here  mentioned, 
so  much  of  it,  or  of  soda  in  its  stead,  were  employed,  as  would  suf- 
fice first  to  precipitate,  and  afterwards  re-dissolve,  the  alumine,  the 
latter,  being  then  in  a  triple  combination  with  the  acid  and  alkali, 


Philosophy  of  Permanent  Colours.  285 

Cotton,  treated  in  this  way,  commonly  gains  about  two 
and  a  half  per  cent,  additional  weight  by  the  alum,  partly 
decomposed,  which  combines  with  it.  But,  where  no 
white  grounds  are  to  be  reserved,  thtre  are  ways  of 
separating  the  aluminous  basis  more  advantageously, 
and  applying  it  more  efficaciously,  particularly  for  mad- 
der colours  upon  linens  and  cottons,  by  impregnating 
them  with  oleaginous,  astringent,  glutinous,  animal,  and 
alkaline  substances,  which  occasion  an  increased  affinity 
or  attraction  between  the  fibres  of  the  linen  or  cotton  and 
the  colouring  matters;  thereby  forming,  perhaps,  a  kind 
of  cement,  which  renders  them  more  fixed,  and  less 
liable  to  be  acted  upon  and  injured  by  those  causes 
which  generally  destroy  or  weaken  colours.  These  aux- 
iliary means  will  hereafter  be  noticed  in  their  proper 
places,  and  particularly  when  treating  of  the  Turkey 
red. 

Silk  is  to  be  impregnated  with  the  aluminous  basis, 
by  macerating  or  soaking  it  only,  during  the  space  of 
ten  or  twelve  hours,  in  a  saturated  cold  solution  of  alum. 

To  impregnate  wool  or  woollen  cloth  with  the  alumi- 
nous basis,  it  is  commonly  boiled  in  water,  with  from 
one  fourth  to  one-sixth  of  its  weight  of  alum,  and  from 
one-twelfth  to  one-sixteenth  of  its  weight  of  crude  tartar, 
putting  the  latter  first  into  the  water,  and,  afterwards, 
the  powdered  alum:  the  heat  of  the  water  being  gradu- 
ally raised,  is  kept  at  the  boiling  point  for  an  hour  and 
a  half,  or  two  hours,  during  which  the  cloth  is  turned 
through  the  boiling  liquor  on  a  winch,  that  the  mordant 
may  be  equally  applied;  and  being  afterwards  taken  out 
and  drained,  it  is  commonly  left  until  the  next  day,  and 
then  rinced  in  clean  water,  for  dyeing.  In  the  early  col- 
would  be  less  attached  to  either,  and  more  readily,  as  well  as  co- 
piously separated,  and  united  with  the  fibres  of  linen  or  cotton. 


286  Philosophy  of  Fermanent  Colours. 

lection  of  recipes,  printed  in  1605,  and  already  men- 
tioned, sour  bran  liquor  is  commonly  directed  to  be 
employed  in  this  way  with  alum;  and  it  seems  to  have 
answered  the  purpose  of  tartar,  which,  when  it  came  to 
be  generally  used  in  this  way  with  alum,  was  supposed 
by  the  older  dyers  to  do  good  by  softening  and  correct- 
ing the  acrimony  of  the  latter:  probably,  however,  the 
purposes  which  it  answers,  are  not  yet  clearly  ascertain- 
ed; one  of  them  seems  to  be,  that  of  increasing  the 
solubility  of  alum,  and  enabling  it  more  completely  and 
intimately  to  penetrate  the  fibres  of  the  wool,  with  which 
it  moreover  enters  into  a  permanent  union,  and  thereby 
contributes  efficaciously  to  modify,  vary,  and  in  some 
cases  to  brighten  the  colours  with  which  it  is  employed, 
as  will  be  seen  hereafter. 

It  was  until  very  lately  believed,  even  by  those  who 
had  most  knowledge  of  the  subject,  that  woollen  cloth 
boiled  in  this  way,  with  alum,  decomposed  the  latter, 
in  a  considerable  degree  at  least,  attaching  to  itself  the 
alumine,  though  not  without  a  small  portion  of  the  sul- 
phuric acid  in  combination  therewith.*  Very  recently, 
however,  MM.  Thenard  and  Roard  (of  whom,  the  lat- 
ter is  director  of  the  dyeing  department  at  the  imperial 
manufactory  of  the  Gobelins  at  Paris,)  appear  to  have 
acquired  more  correct  ideas  on  this  point,  by  a  series 
of  experiments,  of  which  they  have  given  a  minute  state- 
ment, in  a  memoir  read  at  the  Physical  and  Mathemati- 
cal class  of  the  French  National  Institute,  (see  Ann.  de 
Chimie,  tom.  74,  p.  267.) 

*  Berthollet,  tom.  i.  p.  80,  after  saying,  that  in  aluming  stuffs 
the  latter  decompose  the  alum,  and  combme  with  the  alumine, 
whilst  the  acid  which  held  it  dissolved,  separates  and  remains  in 
the  bath,  adds,  "  Mais  il  ne  faudrait  pas  conclure  de  la,  qu'aucune 
portion  de  Tacide  ne  reste  dans  la  combinaison  de  retoffe  ou  elle 
peut  avoir  quelque  influence  sur  la  couleur." 


Philosophy  of  Permanent  Colours.  287 

These  experiments  were  principally  made  with  alum, 
acetate  of  alumine,  tartar,  and  the  solutions  of  tin,  applied 
to  wool,  silk,  and  cotton;  and  by  these,  it  was  fully  as- 
certained, that  alum  and  cream  of  tartar  do  not  decom- 
pose each  other  when  dissolved  in  water,  and  boiled 
with  wool,  (a  fact  which  had,  indeed,  been  previously 
asserted  by  Berthollet);  that  in  this  boiling,  the  wool 
combines  with  the  alum,  without  decomposing  it  in  any 
degree ^"^  and  also  with  the  tartar;  that  equal  parts  of  alum 
and  tartar  would  dissolve  in  two  fifths  less  of  water,  than 
would  be  required  to  dissolve  them  separately. 

They  found  that  wool,  as  it  is  commonly  cleansed  for 
being  alumed,  was  not  deprived  of  the  carbonate  of  lime 
naturally  combined  with  it;  and  that  this  wool,  being 
boiled  the  usual  time,  with  one- fourth  of  its  weight  of 
alum,  and  one-sixteenth  of  its  weight  of  cream  of  tartar, 
rendered  the  bath,  or  water,  troubled  or  muddy,  and 

*  It  was  completely  ascertained,  that  when  wool  had  been  so 
alumed^  the  alum  employed  might  be  all  recovered,  partly  from  the 
bath  or  liquor  in  which  the  aluming  had  been  performed,  and  partly 
from  the  wool  itself,  by  repeatedly  washing  the  latter  in  pure  boil- 
ing water:  commonly  a  dozen  separate  washings  were  sufficient  to 
remove  completely  all  the  alum  which  had  united  itself  to  the  wool; 
and  the  alum,  so  separated,  was  susceptible  of  a  distinct  crystalli- 
zation, as  if  it  had  never  been  so  employed.  After  the  last  of  these 
washings,  the  wool  or  cloth,  so  washed,  was  found  to  be  as  incapa- 
ble of  receiving  colours  by  dyeing,  as  if  it  had  not  been  alumed;  and, 
indeed,  before  the  lasty  it  was  always  found,  that  the  colour  attempted 
to  be  dyed  upon  it,  was  feeble,  in  proportion  to  the  number  of  wash- 
ings which  had  taken  place. 

It  became  evident,  therefore,  from  these  experiments,  that  wool 
or  cloth  boiled  with  alum  (and  tartar)  attached  to  itself  the  unde- 
comfiosed  alum  only,  and  that  a  decomposition  of  the  latter  does  not 
take  place  until  the  subsequent  operation  of  dyeing,  when  the  affi- 
nity of  v;ool,  being  assisted  in  the  dyeing  vessel,  by  the  affinity  of 
the  adjective  colouring  matter,  iheir  c a- opera tioji  separates  the  alu- 
mine, in  a  great  degree  at  least,  from  the  sulphuric  acid. 


288  Philosophy  of  Permanent  Colours, 

produced  (as  is,  indeed,  commonly  observed),  a  copious 
white  sediment,  which  being  collected,  washed,  and  ana- 
lysed, was  found  to  consist  chieflv  of  a  sulphate  of  lime, 
and  a  saturated  sulphaie  of  alumine.  That  when  wool 
had  been  properly  cleansed,  and  deprived  of  its  carbo- 
nate of  lime,  no  sulphate  thereof  was  found.  Such  wool 
or  cloth,  being  boiled  in  pure  distilled  water,  with  the 
proportions  just  mentioned  of  alum  and  tartar,  and  the 
bath  or  liquor  with  which  the  boiling  had  been  perform- 
ed being  carefully  evaporated,  a  residuum  was  found, 
consisting  of  alum,  cream  of  tartar,  and  a  compound, 
difficultly  crystallizable,  of  tartrite  of  potash  and  animal 
matter.  The  wool  itself,  when  so  boiled,  afforded,  by 
repeated  washings,  alum,  and  a  small  quantity  of  cream 
of  tartar,  besides  a  very  sour  combination  of  tartaric 
acid,  alum,  and  animal  matter.  As  the  acid  of  tartar 
combines  so  copiously  with  wool,  MM.  Thenard  and 
Roard  have  inferred,  that  it  ought  not  to  be  employed 
in  this  way  with  alum,  except  for  colours  which  acids 
contribute  to  raise  and  improve;  and  among  such  co- 
lours they  rank  those  of  cochineal,  kermes,  and  madder; 
but  those  of  weld,  logwood,  and  Brasil  wood,  not  resist- 
ing acids  as  thty  suppose,  wool,  intended  to  be  dyed 
from  either  of  these,  ought,  as  they  think,  to  be  alum- 
ed,  without  any  addition  of  tartar.  The  accuracy  of 
these  opinions  will  be  tried  by  facts,  when  the  several 
colouring  matters  here  mentioned  shall  claim  our  parti- 
cular  attention. 

These  gentlemen  did  not  find  any  advantage  to  arise 
by  a  prolongation  of  the  boiling  with  alum  and  tartar 
beyond  the  space  of  two  hours,  nor  by  increasing  the 
proportions  of  alum  and  tartar;  but,  on  the  contrary, 
thought  they  observed  beneficial  effects  from  a  diminu- 
tion of  them  with  weld,  logwood,  and  Brasil  wood,  but 
not  with  cochineal,  madder  or  kermes.  Nor  did  they 


Philosophy  of  Permanent  Colours.  289 

find  any  benefit  produced,  by  letting  the  wool  or  cloth 
remain  some  days  in  the  liquor  with  which  it  had  been 
boiled,  as  some  persons  have  advised. 

From  these  experiments,  MM.  Thenard  and  Roard 
have  thought  themselves  entitled  to  conclude,  with  ''  cer- 
titude, que  dans  Talunage  de  toutes  les  matieres  anima- 
les,  I'alun  se  combine  en  entier  avec  elles,  sans  epcouver 
aucune  decomposition,  et  qu'il  forme  alors  des  combi- 
naisons  plus  ou  moins  solubles,  qui  ont  pour  les  ma- 
tieres colorantes  une  grande  afiinite;"  and  they  have 
made  a  similar  conclusion  in  regard  to  vegetable  matters, 
(i.  e.  linen  and  cotton,  &c.);  having  found  that  the  latter, 
when  carefully  alumed,  might  be  completely  deprived 
of  every  particle  of  alum,  by  fewer  washings  than  silk, 
and  by  much  fewer  than  wool,  which  had  been  so  alum- 
ed. They  found  also  that,  (as  with  silk,*^  and  for  similar 
reasons),  it  was  always  best  to  begin  the  dyeing  of  linen 
and  cotton  (when  alumed)  at  a  low  temperature,  and  to 
keep  the  dyeing  liquor  considerably  below  the  boiling 
point,  until  the  colouring  matters  were  enabled  to  at- 
tach  themselves  to  the  mordant,  and  produce  an  insolu- 
ble combination  therewith,  previously  to  its  being  sub- 
jected to  the  action  of  boiling  water. 

These  gentlemen,  moreover,  ascertained,  that  when 
acetate  of  alumine  was  applied  to  wool,  silk,  linen,  and 
cotton,  it  combined  with  them  entirely,  undecomposed, 
like  alum;  but,  being  exposed  to  a  warm  atmosphere,  a 
part  of  the  acetic  acid,  from  its  volatility,  soon  evapo- 
rated, leaving  behind  an  excess  of  alumine,  which  could 

*  Silk  ought  never  to  be  subjected  to  a  boiling  heat,  either  when 
the  mordant  is  applied,  or  afterwards,  in  the  dyeing  operation; 
where  a  high  temperature,  besides  injuring  the  texture  and  lustre 
of  the  silk,  would  detach  and  separate  the  mordant,  before  the  co- 
louring matter  could  have  combined  and  produced  an  insoluble 
union  with  both. 

Vol.  I.  2  O 


290  Philosophy  of  Permanent  Colours. 

not,  like  the  mere  acidulated  acetate  of  alumine,  be 
carried  off  by  boiling  water:  a  fact  which  accords  with 
the  explanation  lately  given  of  the  utility  of  this  mor- 
dant in  calico-printing. 

In  regard  to  the  solutions  of  tin,  it  appears,  that  wool- 
len cloth,  boiled  with  them  in  water,  and  the  proportion 
of  tartar  which  is  commonly  employed  in  dyeing  scar- 
let, combined  with  the  acids,  as  well  as  with  the  oxide 
of  that  metal;  and  that  by  numerous  washings  after- 
wards with  distilled  water,  boiling  hot,  all  these  matters 
were  completely  separated;  and  that  by  evaporating  the 
washings,  they  were  collected  in  the  form  of  tartaric 
acid,  and  muriatic  acid,  combined  with  tin;  while  the 
mother  water  contained  (as  was  also  ascertained  by  eva- 
porating it)  tartrite  of  potash,  acidulated  tartrite,  and  a 
very  acid  muriate  of  tin.  It  results,  therefore,  from 
these  experiments,  that  wool  has  no  more  power  to 
decompose  the  solutions  of  tin,  than  it  has  to  decom- 
pose those  of  alum;  and  that,  when  not  assisted  by  the 
affinity  of  some  colouring  matter,  it  unites  with  both 
the  tin  and  the  acids,  holding  them  in  solution. 

The  different  solutions  of  tin,  the  best  means  and 
methods  of  producing  them,  and  their  respective  effects 
in  dyeing,  will  be  noticed  hereafter;  and  more  especially 
when  I  come  to  treat  of  the  dyeing  of  scarlet  with  co- 
chineal, for  which  that  metal  was  first  employed  as  a 
mordant,  and  with  advantages  so  remarkable,  that  the 
discovery  of  its  use  for  that  purpose,  may  be  consider- 
ed as  an  important  aera  in  the  history  of  this  art. 

The  mordants  afforded  by  iron,  when  employed  upon 
wool  and  silk,  are  commonly  applied  either  subsequently 
to,  or  interchangeably  with,  the  colouring  matters  in- 
tended to  be  fixed  or  modified  by  that  basis,  as  will  be 
more  particularly  explained,  when  the  dyeing  of  black 
claims  our  attention. 


Philosophy  of  Permanent  Colours.  291 

It  will  be  ascertained  hereafter,  by  my  own  particular 
experiments,  that  all  the  metals,  properly  so  called,  as 
far  as  they  have  been  tried,  are  capable  of  attracting  ad- 
jective colouring  matters  in  some  degree,  and  of  serving 
as  bases  to  them;  and  this  is  also  true  of  most  of  the 
earths;  though  none  of  them  is  so  efficacious  and  useful 
in  this  way  as  alumine;  indeed  this,  and  the  oxide  of 
tin,  seem  to  be  the  only  bases  suited,  by  their  perfect 
whiteness^  to  reflect  the  rays  of  light  so  as  to  exhibit 
adjective  colours  with  their  utmost  lustre  and  bright- 
ness, every  other  falling  short  of  these  in  that  respect, 
and  almost  all  of  them  appearing  to  sadden  or  darken 
the  colours  which  they  serve  to  fix.  Probably,  the 
oxides  of  zinc  and  antimony  do  this  less  than  any  of 
the  others:  the  former,  however,  (zinc)  does  not  appear, 
by  my  experiments,  capable  of  giving  much  stability 
and  permanency  to  any  colour  dyed  with  it. 

After  this  general  explanation  and  illustration  of  the 
properties  and  uses  of  mordants  or  bases  in  fixing  and 
mpdifying  adjective  colours,  I  shall  next  proceed  to  a 
particular  inquiry  concerning  their  effects  upon  each  of 
the  more  important  dyeing  drugs  of  this  class,  begin- 
ning with  those  which  belong  to  the  animal  kingdom. 


29tS[  Philosophy  of  Permanent  Colours, 


CHAPTER  II. 

Of  Adjective  Colours  from  European  Insects^  and  prin- 
cipally from  the  Kermes,  or  Coccus  Ilicis,  Linn, 

"  La  laine  et  la  soie  qui  montreroient  plutot  dansleurcouleurnaturellelarusticite 
*•  de  I'age,  que  I'esprit  de  I'homme  etla  politesse  du  siecle,  n'auroient  qu*un  mediocre 
*'  commerce,  si  la  teinture  ne  leur  donnoft  des  agremens  qui  les  font  rechercher  et 
"  desirer,  merae  par  les  nations  les  plus  barbares." 

Colbert,  Instrnction  g^n^rale  potir  la  Teinture,  &c.  1672. 

Among  animal  adjective  colours,  the  kermes  are  enti- 
tled to  our^r^^  notice,  because  they  appear  to  have  been 
used  for  dyeing  at  a  very  early  period;  and,  like  the 
murex  and  buccinum,  were  probably  first  employed  for 
that  purpose  by  the  Phoenicians,  Being    unacquainted 
with  the  oriental  languages,  I  can  only  adduce  to  this 
point  the  opinions  of  others,  better  qualified  than  myself 
in  that  respect.  One  of  these  is  Professor  Tychsen,  (quo- 
ted by  professor  Beckman,  vol.  ii.  p.   185  of  the  Eng- 
lish translation  of  his  History  of  Inventions,)  who  says, 
that  among  the  Hebrews,  the  kermes  dye  was  mentioned^ 
under  the  names  of  *'  tola  schant,  or  simply  tola^  by  their 
oldest  writer,  Moses;"  that  *'  tola  is  properly  the  worm^"^^ 
and  that  "  the  additional  word  schani,  signifies  either 
double  dyed,  or,  according  to  another  derivation,  bright, 
deep,  red  dye;"  that  for  the  shell  ''  purple,  the  orientals 
have  a  particular  name,  argaman  or  argevan^  which  is 
accurately  distinguished  from  fo/a;" — ''  all  the  ancients, 
therefore,  translate  the  Hebrew  word  tola  by  xoxjco?,  Ker- 
mes, zehori,  and  zehorito,  (deep  red,  bright  dye,)  which 
words  they  never  put  for  argaman."  After  these  and  other 
observations,  he  concludes,  that  '*  the  scarlet,  or  kermes 
dye  was  known  in  the  East,  in  the  earliest  ages  before 
Moses;  and  was  a  discovery  of  Phoenicians  in  Palestine, 
hut  certainly  not  of  the  small  wandering  Hebrew  tribes." 


Philosophy  of  Permanent  Colours,  293 

That  "  tola  was  the  ancient  Phoenician  name  used  by 
the  Hebrews,  and  even  by  the  Syrians;  for  it  is  employ- 
ed by  the  Syrian  translator,  Isaiah,  chap.  i.  v.  18." — 
"  Among  the  Jews,  after  their  captivity,  the  Aramaan 
word  zehori  was  more  common." 

BischofF  also  maintains,  that  the  kermes  red  dye  was 
meant  by  the  Hebrew  words  tholaat  schani,  in  several 
parts  of  the  Old  Testament.  It  may,  therefore,  be  assu- 
med, that  the  colour  which  is  mentioned  in  Exodus, 
chapters  xxvi.  xxviii.  and  xxxix.  (as  one  of  the  three 
which  were  prescribed  for  the  curtains  of  the  tabernacle, 
and  for  the  **  holy  garments"  for  Aaron,)  and  which  the 
English  translators  have  rendered  by  the  word  scarlet, 
(as  they  have  done  in  other  parts  of  the  Old  Testament) 
was  no  other  than  the  blood-red  colour,  dyed  from  the 
kermes.  Indeed  the  colour  now  denominated  scarlet,  and 
dyed  from  cochineal^  upon  a  tin  basis,  had  not  been  dis- 
covered when  the  last  English  version  of  the  Bible  was 
made,  in  the  reign  of  James  the  First. 

The  Greeks  appear  to  have  obtained  a  knowledge  of 
the  kermes,  and  their  use  in  dyeing,  at  a  much  later  pe- 
riod; and  we  find  this  insect  denominated  kokko?  lix(piK>j 
by  Dioscorides,  iv.  48,  p.  260,  and  by  other  Greek  wri- 
ters: whence  the  Latins  derived  their  names  of  coccum 
or  coccus,  with  the  addition  of  infectoris,  or  infectorium. 
Pliny,  as  I  have  noticed  at  p.  93,  mentions  the  kermes 
as  being  sometimes  employed,  conjointly  with  the  colour 
of  the  murex  and  buccinum,  in  producing  a  sort  of  pur- 
plish crimson,  called  by  the  Romans  hysginus.  He  adds, 
upon  that  occasion,  that  this  drug  was  brought  from 
Galatia,  or  from  the  vicinity  of  Emerita,  in  Portugal,  and 
that  the  latter  was  the  most  commended.*  And  again, 

*  "  Coccum  Galatiae  rubens  granum^* — "  aut  circa  Emeritam 
r.usitaniae,in  maxima  laude  est."  Plin.  Hist.  lib.  ix.  c.  41. 


294  Philosophy  of  Permanent  Colours. 

in  his  16th  book,  chapter  viii.,  after  describing  various 
uses  or  products  of  the  oak,  he  mentions  the  coccum, 
or  kermes,  as  being  the  most  excellent;  adding,  that  it 
is  an  excrescence,  produced  upon  the  stems  of  a  small 
shrub,  called  the  ilex  aquifolia; — but  of  such  value,  that 
the  people  of  Spain  are  enabled  to  discharge  half  their 
tribute  by  it;  and  that  it  is  also  produced  in  Galatia, 
Africa,  Pisidia,  &c.  Lastly,  Pliny,  in  the  second  chapter 
of  his  twenty- second  book,  after  noticing  the  great  im- 
provements w^hich  had  been  then  recently  made  in  the 
art  of  dyeing,  mentions  (while  he  professes  to  pass  over) 
the  grains  brought  from  Galatia,  Africa,  and  Portugal, 
and  appropriated  for  dyeing  the  imperial  robes,  &c.* 

The  ancients  had  but  very  incorrect  notions  of  the 
kermes,  many  supposing  them  to  be  the  grains  or  fruit 
of  the  ilex.  They  saw,  indeed,  that  insects  were  ulti- 
mately evolved  or  produced  from  them;  but  believing, 
as  they  did,  that  insects  might  be  spontaneously  genera- 
ted by  corruption,  this  evolution  did  not  appear  incom- 
patible with  their  supposition,  that  the  kermes  was  pro- 
perly the  grain,  or  berry,  of  the  tree  on  which  it  was 
found. 

From  the  name  of  coccum  or  coccus,  cloth  dyed  red 
with  kermes  was  designated  by  the  substantive  cocci- 
num,  and  the  adjective  coccinus,  or  coccineus;t  and 

*  "  Atque  ut  sileamus,  Galatiae,  fricae,  Lusitaniae  granis,  coc- 
cum hnfieratoriia  dicatum  paludamentis,"  &c. 

t  Corresponding  designations  were  given  in  tlie  original  Greek, 
as  well  as  in  the  Latin  version  of  St  Matthew,  xxvii.  v.  28,  to  the 
robe  which  our  translators  denominate  scarlet,  and  with  which  the 
soldiers  clothed  and  derided  Jesus,  when  having  <*  platted  a  crown 
of  thorns,  they  put  it  upon  his  head,  and  a  reed  in  his  right  hand, 
and  they  bowed  the  knee  before  him,  and  mocked  him,  saying,  Hail, 
king  of  the  Jews."  The  fact  shows,  that  the  kermes  red  was  then 
considered  as  an  attribute  of  royalty. 


Philosophy  of  Permanent  Colours.  295 

persons  wearing  such  cloth  were  said  to  be  coccinati, 
according  to  the  following  line  of  Martial,  viz. 
"  Qui  coccinatoa  non  putat  viros  esse." 

It  will  have  been  seen,  by  the  passages  which  I  have 
recently  quoted  from  Pliny,  that  the  appellation  of 
granum  was  given  by  him  to  the  kermes  insect,  doubt- 
less from  its  resemblance  to  a  grain  or  berry;  and  this 
appellation  has  been  continued  by  succeeding  writers*, 
and,  doubtless,  occasioned  the  colours  dyed  from  the 
kermes  to  be  called  grain,  or  ingrain  colours,  as  those 
of  cochineal  afterwards  were,  from  a  similar  mistake, 
which  for  some  time  subsisted,  concerning  the  nature 
of  that  insect. 

By  a  succession  of  observations,  however,  it  seems 
to  have  been  ultimately  ascertained,  that  the  worm  or 
insect  was  the  most  important  part  of  the  supposed 
grain  or  berry  in  producing  the  kermes  red,  and,  there- 
fore, in  what  have  been  called  the  middle  ages,  this 
production  was  frequently  denominated  vermiculus^  or 
vermiciilumy  and  the  cloth  dyed  with  it  vermiculata; 
and  hence  ultimately  originated  the  French  word  ver- 
meil, and  that  of  vermilion  derived  from  it. 

The  Spaniards,  and  through  them  the  other  nations 
of  Europe,  appear  to  have  obtained  the  name  of  kermes 
from  the  Arabians,  who,  according  to  their  own  ac- 
counts, were  made  acquainted  with  it,  as  well  as  the 
substance,  by  the  Armenians!  and  Persians,  among 

*  In  modern  times,  the  kermes  have  been  called  by  the  Italians, 
^ana  da  tintore;  by  the  Spaniards, ^rana  de  tinctores;  by  the  French, 
graine  d'escarlate;  and  by  the  English,  kermes  berries. 

t  Beckman  says,  that  J.  Beithar,  in  Bochart  Hierozoicon,  ii.  p. 
625,  calls  kermes  an  Armenian  dye;  and  that  the  Arabian  lexico- 
graphers, from  whom  Giggeus  and  Castellus  made  extracts,  ex- 
plain the  kindred  word  karmasal,  (coccineus  sou  vermiculatus)  as 
an  jirmenian  word.  It  is  notorious  that  the  insects  in  question 


296  Philosophy  of  Permanent  Colours. 

whom  (as  has  been  mentioned  by  Dioscorides,  Dodo- 
neus,  and  others)  kermes  was  an  indigenous  production, 
and  had  for  many  ages  been  employed  in  dyeing.  By 
thus  adopting  the  name  of  kermes,  the  Italians  after- 
wards produced  from  it  the  words  chermisiy  cremesino, 
and  chermesino;  and  the  French  those  of  carmesin,  car- 
mine, and  cramoisi;  whence  the  English  word  crimson 
was  borrowed. 

The  origin  or  derivation  of  the  name  escarlatum,  scar- 
letum,  scarlata,  squarlata,  scarlatina,  or  scharlatica,  from 
which  the  French  escarlate  or  ecarlate,  and  the  English 
scarlet  have  been  formed,  is  more  uncertain:  Pezronius 
thought  it  of  Celtic  extraction;  and  that  it  signified  ga- 
laticus  rubor,  (See  Antiq.  Celt.  p.  69.)  But  according  to 
Beckman,  Stiler  asserts  that  scarlach  is  a  German  word, 
compounded  of  schor^  fire,  and  lacken,  cloth:  and  con- 
sequently that  it  signifies  fire-coloured  cloth:  while 
Reiske,  on  the  contrary,  derives  the  words  in  ques- 
tion from  the  Arabic  scharaly  meaning  the  kermes  dye. 

It  may  be  observed  in  favour  of  Stiler's  assertion, 

have  long  been  produced  and  employed  for  dyeing,  both  in  Ar- 
menia and  Persia;  and  that  they  were  there  called  kermes^  may 
be  proved  among  other  testimonies  by  the  following  extract  from 
Sir  John  Chardin's  account  of  Persia,  published  in  Harris's  Collec- 
tion of  Voyages,  where,  treating  of  Media,  he  says,  *'  they  gather 
cochineal,  though  in  no  great  quantity,  nor  for  any  longer  time 
than  eight  days  in  summer,  when  the  sun  is  in  Leo;  for  before  that 
time  the  people  say  it  doth  not  come  to  maturity;  and  after  it,  the 
ivorm  from  which  they  draw  the  cochineal,  makes  a  hole  in  the  leaf 
in  which  it  grows,  and  is  lost.  The  Persians  (he  adds)  call  cochi- 
neal kermes  from  yterm,  which  signifies  a  worm^  because  it  is  ex- 
tracted out  of  worms."  It  can  hardly  be  necessary  to  remark,  that 
the  term  cochineal  is  here  improperly  used,  and  that  nothing  more 
is  meant  by  it,  than  the  colouring  matter  of  the  kermes;  which  con- 
tinues, according  to  the  best  information  that  I  can  procure,  to  be 
employed  in  a  great  part  of  India,  as  well  as  Persia,  particularly 
for  the  dyeing  of  silk. 


Philosophy  of  Permanent  Colours.  297 

that  the  kermes  red  has  in  different  ages  been  compared 
to  the  colour  of  fire,  I  have  seen  the  words  "  ardenti 
radiabat  Scipio  coccoC"*  in  some  of  the  Latin  classics, 
though  I  cannot  recollect  which.  And  Bi.>choff,  on  the 
authority  of  Muratori,*  mentions  an  old  charter  or  con- 
tract passed  in  the  year  1194,  between  the  cities  of  Bo- 
logna and  Ferrara,  by  which  a  duty  was  to  be  levied  in 
the  former  of  these  cities,  upon  the  grana  de  Brasile, 
meaning  kermes,  (and  upon  indigo);  and  he  adds,  that 
these  Brasilian  grains,  and  also  Brasil  wood,  are  men- 
tioned in  other  old  charters,  particularly  one  dated  in 
1198,  and  another  in  1306,  under  the  name  of  Braxilis; 
and  he  concludes,  with  great  probability,  that  this,  and 
the  word  brasilis,  were  derived  from  bragio,  a  burning 
coal;  in  the  French  braise:  and  we  shall  accordingly  find 
hereafter,  that  red  dyeing  woods,  similar  to  that  now 
called  Brasil  wood,  were  distinguished  by  that  name, 
before  any  such  wood  was  known  or  suspected  to  be 
produced  in  that  part  of  America  now  called  Brasil;  and 
that  this  name  was  given  to  that  country  many  years  af- 
terwards, when  the  wood  came  to  be  thence  imported; 
and  consequently  that  the  country  obtained  the  name 
from  the  wood,  and  not  the  wood  from  the  country. 

At  what  time  the  words  from  which  our  scarlet  was 
derived  were  first  used,  cannot,  I  believe,  now  be  accu- 
rately ascertained;  the  most  early  employment  of  them, 
of  which  I  have  found  an  instance,  is  that  which  Beck- 
man  has  quoted  from  the  Historia  Gelrica  Pontani, 
(Hordervici  1639,)  in  which,  about  the  year  1050,  the 
emperor  Henry  III.  conferred  upon  the  Count  of  Cleves, 
the  Burgraviate  of  Nimeguen,  on  the  condition  of  his 
delivering  to  him  annually  three  pieces  of  scarlet  cloth, 

*  Dissert,  de  Mercatibus  et  Mercatura  saeculorum  rudium,  tom. 
ii.— Antiquitat.  diss.  xxx.  p.  898. 
Vol.  I.  2  P 


298  Philosophy  of  Permanent  Colours. 

made  of  English  wool  ("  tres  pannos  scarlatinos  anglica^ 
nos,^^)  Beckman  also  refers  to  a  document  in  Lunig's 
Codex  Diplom.  Germaniae,  ii.  p.  1739,  by  which  the 
emperor  Frederick,  in  1217,  conferred  on  the  Count  of 
Giieldres,  the  hcreditable  jurisdiction  of  Nimegnen,  on 
condition  that  he  and  his  successors,  "  de  eodem  telo- 
nio,  singulis  annis  tres  pannos  scarlacos  bene  riibeos 
anglicenses  ardentis  coloris  assignare  deberet."  The 
selection  of  English  cloth,  in  these  instances,  demon- 
strates the  high  estimation  in  which  it  was  held  even  at 
those  periods.  Beckman  also  refers  to  "  Gervasii  Tilbe- 
riensis  Otia  Imperialia  ad  Ottonem  iv,  Imperatorem, 
iii.  S5\^^  a  work  written  in  1211,  in  which  the  author 
alluding  to  the  kermes  says,  "  Vermiculus  hie  est,  quo 
tinguntur  pretiosissimi  regum  panni,  sive  serici,  ut  ex- 
amiti,  sive  lanei,  ut  scharlatay  And  he  then  mentionb  it 
as  wonderful  that  neither  linen,  nor  any  other  vegetable 
substance,  would  permanently  take  this  dye,  "  sed  sola 
vestis  quae  ex  vivo  animanteque,  vel  quo  vis  animato 
decerpilur."  He  afterwards  mentions  the  shrub  on  which 
the  kermes  were  found,  and,  like  Dioscorides,  compares 
the  latter  to  peas^  in  regard  to  their  shape  and  size; 
addjng,  "  cum  enim  tempus  solstitii  aestivi  advenerit, 
ex  seipso  vermiculos  generat,  et  nisi  coriis  subtiliter 
consutis  includerentur,  omnes  fugerent,  aut  in  nihilum 
evanescerent.  Hinc  est  quod  vermiculus  nominatur, 
propter  dissolutionem  quam  in  vermes  facile  facit,  ex 
natura  roris  maialis,  a  quo  generatur;  unde  et  illo  tan- 
tum  mense  colligitur."  We  see  by  the  latter  part  of  this 
extract,  that  the  kermes  were  not  at  that  time,  as  at  pre- 
sent in  France  and  Spain,  killed  by  being  sprinkled  with 
vinegar  and  dried  in  the  sun;  and  therefore,  to  prevent 
their  ultimate  escape,  they  were  secured  by  being  put 
into  leathern  bottles. 

Besides  these  instances  of  the  early  mention  of  sear- 


Philosophy  of  Permanent  Colours,  299 

let,  it  occurs  in  several  books,  written  in  the  thirteenth 
century;  such  as  the  History  of  Spain,  by  Roderick 
archbishop  of  Toledo,  (lib.  vii.  1.),  which  was  finished 
in  1243;  and  in  some  quoted  by  Vossius,  '*  de  vitiis 
sermonis,  4°."  Others  might  be  added  to  these,  were 
they  necessary. 

At  the  periods  when  the  terms  cscarlatum,  &c.  were 
thus  employed,  the  art  of  dyeing  purple  from  the  murex 
and  buccinum  was  lost  in  the  western  empire,  and  the 
kermes  dye,  which  in  former  times  had  been  almost  as 
much  esteemed,  was  become  pre-eminent  and  unri- 
valled; and  so  it  continued,  until  the  introduction  of 
cochineal,  from  America,  (to  be  noticed  in  my  next 
chapter)  which  has,  in  great  degree,  put  an  end  to  the 
use  of  kermes  in  Europe,  though  the  acorn-bearing 
shrub,  which  the  ancients  called  ilex,  (and  which,  in 
the  Linnaean  system,  is  denominated  quercus  coccifera,) 
still  grows,  and  furnishes  these  insects,  in  all  the  coun- 
tries mentioned  as  formerly  producing  them;  and  though 
the  insects  themselves  continue  to  be  employed  in  other 
parts  of  the  world,  and  with  great  reason,  for  in  truth 
they  are  capable,  as  my  own  experiments  prove,  of  giv- 
ing every  colour  which  can  be  obtained  from  cochineal 
with  equal  beauty  and  vivacity,  and  perhaps  with  even 
greater  permanency. 

The  first  volume  of  the  Philosophical  Transactions 
contains  a  paper,  written  by  M.  Verney,  then  of  Mont- 
pellier,  respecting  the  natural  history  of  the  kermes;  and 
M.  Reaumur  afterwards  described  them  very  minutely 
in  the  fourth  volume  of  his  "  Memoires  pour  servir  a 
I'Histoire  des  Insectes."  But  the  most  useful  informa- 
tion on  this  subject  seems  to  be  that  which  M.  Chaptal 
lately  gave  to  M.  Berthollet,  and  which  he  has  pub- 
lished  in  the  second  volume  of  his  '*  Elemens  de  TArt 
de  la  Teinture,"  By  his  account,  the  male  insect  passes 


300  Philosophy  of  Permanent  Colours. 

from  its  vermicular  state,  through  the  usual  forms,  into 
that  of  a  fly  with  four  wings;  though  the  female  never 
acquires  any  wings,  but  fixes  herself  on  a  leaf  of  the  oak, 
where,  being  impregnated  by  the  male,  her  size  gradu- 
ally increases  (as  the  ^ggs  enlarge)  to  that  of  a  juniper- 
berrv,  and  she  at  the  same  time  becomes  of  a  reddish 
brown  colour.  When  the  eggs  are  on  the  point  of  hatch- 
ing, the  females  should  be  collected,  and  exposed  to  the 
steam  of  vinegar,  to  kill  them,  and  prevent  their  young 
from  being  brought  forth;  and  afterwards  they  should 
be  dryed,  by  being  spread  out  on  cloths,  by  which  treat- 
ment they  acquire  the  colour  of  red  wine.  M.  Chaptal 
says,  that  a  single  person  may  collect  from  one  to  two 
pounds  of  kermes  in  a  day.  But  it  would  require  ten  or 
twelve  pounds  to  produce  the  effect  of  a  single  pound  of 
cochineal;  and  as  the  kermes,  probably,  could  not  be  ob- 
tained in  any  quantity  for  less  than  half-a-crown  the 
pound,  the  colour  which  they  afford,  would  prove  more 
costly  than  that  of  cochineal,  at  the  price  which  the  latter 
has  commonly  borne  previous  to  the  present  war. 

Hcllot  tells  us,  chapter  xii.  that  the  red  draperies  of 
the  figures  exhibited  in  the  ancient  Brussels  and  other 
Flemish  tapestries,  were  all  dyed  from  kermes,  and  that 
this  colour,  which  in  many  of  them  has  subsisted  more 
than  200  years,  has  lost  but  very  little,  if  any,  of  its  ori- 
ginal vivacity:  and  Beckman  represents  this  as  being 
true  of  some  pieces  of  tapestry,  which  are  believed  to 
have  been  dyed  with  kermes  as  early  as  the  twelfth  cen- 
tury. The  fine  red  or  crimson  colour  of  these  tapestries, 
which  was  originally  called  simply  scarlet,  took  the  name 
of  Fenetian  scarlet,  after  the  cochineal  scarlet  upon  a  tin 
basis  was  discovered,  because,  as  Hellot  mentions,  it 
continued  to  be  extensively  dyed  at  Venice,  long  after  it 
had  become  unfashionable  in  other  parts  of  Europe; 
though  it  appears,  from  my  own  particular  experiments, 


Fhxhsophy  of  Permanent  Colours.  301 

Aat  if  the  kermes,  like  the  cochineal,  had  been  employ^ 
cd  with  a  solution  of  tin  by  nitro- muriatic  acid  (instead 
of  alum),  a  colour  might  have  been  obtained,  which  it 
would  have  been  difficult,  if  not  impossible,  to  distin- 
guish from  the  cochineal  scarlet. 

To  dye  the  Venetian  scarlet,  the  wool,  'according  to 
Hellot,  was  first  boiled  for  half  an  hour  in  water,  with 
about  its  weight  of  bran,  tied  up  in  a  bag;  it  was  then 
removed  into  another  vessel,  and  boiled  two  hours  in 
water  acidulated  by  fermented  bran  liquor,  with  a  fifth 
of  its  weight  of  Roman  alum,  and  half  as  much  red 
tartar;  leaving  the  wool,  after  taking  it  out  of  this  vessel, 
moistened  with  the  same  liquor,  during  six  days;  at  the 
end  of  which,  it  was  dyed  in  clean  soft  water,  with 
powdered  kermes,  allowing  twelve  ounces  of  the  latter 
for  each  pound  of  wool,  and  even  sixteen  ounces,  if  the 
kermes  had  suffered  by  age.* 

When  the  very  extraordinary  effect  of  a  solution  of 
tin,  in  giving  vivacity  and  lustre  to  the  colour  of  cochi- 
neal, had  been  discovered,  (as  will  be  mentioned  here- 
after,) it  might  have  been  expected,  that  the  influence  of 
this  mordant  upon  the  kermes  colour  would  have  been 
tried,  as  a  matter  of  course,  but  I  cannot  any  where  find 
that  this  was  done;  and  it  was  not  until  I  had  dyed  broad- 
cloth in  the  way,  and  with  the  means  commonly  em- 
ployed to  produce  the  scarlet  colour,  substituting  only 

*  In  a  letter  written  by  Mr.  William  Kirkpatrick  to  Dr.  Ander- 
son, lately  Physician-General  in  the  service  of  the  East-India  Com- 
pany, and  dated  Hyderabad^  June  I4th,  1796, 1  find  the  following  pas- 
sage, viz.  "The  silk-dyers  at  this  place  do  not  know  how,  I  believe, 
to  produce  a  scarlet.  To  dye  a  prime  crimson,  they  employ,  to  on6 
seer  of  silk  (fresh  and  white)  one  quarter  seer  of  kermes,  one  quar- 
ter seer  of  alum,  and  one  quarter  seer  of  flowers  of  pisteh  (pistachio,) 
which  I  take  to  stand  in  place  of  the  gall.  The  enclosed  is  a  speci- 
men of  their  prime  crimson."  If  this  account  of  proportions  be  accu- 
rate, the  kermes  of  India  must  yield  more  than  twice  as  much  co- 
lour as  that  of  Europe. 


302  Philosophy  of  Permanent  Colours, 

kermes  for  cochineal,  in  the  proportion  of  twelve  ounces 
of  the  former  for  one  of  the  latter,  that  I  satisfied  myself 
of  the  practicability  of  dyeing  with  the  kermes  a  scarlet 
colour,  in  every  respect  as  beautiful  and  estimable  as  any 
which  can  be  dyed  with  cochineal;  and,  consequently, 
that  if  the  mordant  from  tin  had  been  properly  employed 
with  the  kermes,  there  could  have  been  no  reasonable  mo- 
tive for  giving  a  preference  to  cochineal,  unless  it  was 
found  to  be  ultimately  cheaper  than  the  kermes,  by  rea- 
son of  the  much  greater  proportion  of  colouring  matter 
afforded  by  it. 

Cotton  being  topically  impregnated  with  the  acetate 
of  alumine,  as  for  calico-printing,  and  one-half  of  it  being 
dyed  with  kermes,  it  took  a  full  bright  crimson,  as  the 
other  did  at  the  same  time  with  cochineal;  and  the  co- 
lours so  dyed,  (which  in  appearance  were  exactly  simi- 
lar,) being  washed  and  exposed  to  the  sun  and  air,  ma- 
nifested a  considerable  degree  of  permanency,  though 
not  sufficient  to  make  it  proper  to  employ  them  in  this 
way,  without  an  addition  of  madder;  the  yellowish  red 
colour  of  which  is  greatly  improved  by  the  bright  crim- 
son of  either  of  these  insects.  I  have  thought,  in  this  and 
other  experiments,  that  the  colour  of  the  kermes  was  a 
little  more  durable  than  that  of  the  cochineal;  not  from 
a  difference  in  the  colouring  matters  of  the  insects,  but 
from  the  astringent  vegetable  matter,  or  juice  of  the  oak, 
which  always  accompanies  the  kermes. 

Subsequently  to  my  former  edition,  I  procured  a 
very  sufficient  supply  of  kermes  from  the  South  of 
France,  and  have  tried  them  with  nearly  all  the  metallic 
and  earthy  bases  or  mordants,  and  always  with  very 
nearly  the  same  results  as  were  obtained  with  the  like 
bases  or  mordants  from  cochineal,  and  of  which  an  ac- 
count will  be  given  hereafter;  and  I  conclude,  therefore, 
that  the  animal  part  of  the  colour  of  the  kermes  is  ex- 
acthj  similar  to  the  colour  of  cochineal. 


Philosophy  of  Permanent  Colours.  303 

Art.  II.  Coccus  Polonicus, 
This  is  a  small  round  insect,  in  many  respects  similar 
to  the  kermes,  and  employed  for  nearly  the  same  pur- 
poses, until  the  introduction  of  cochineal  caused  the  use 
of  it  to  be  abandoned,  at  least  in  the  greater  part  of 
Europe.  It  was  mostly  collected  in  the  Ukraine,  and 
other  provinces  of  Poland,  (under  the  name  of  Czer- 
•wiec^)  and  also  in  the  great  duchy  of  Lithuania,  from  the 
roots  of  the  German  knot  grass,  or  perennial  knawel  (scle- 
ranthus  perennis,  Linn.)  The  male  only,  by  a  transforma- 
tion similar  to  that  of  the  male  kermes,  becomes  a  fly, 
though  with  but  two  wings,  which  are  white,  edged 
with  red.  The  females  being  impregnated  by  the  male, 
enlarge  their  size,  and  become  ready  to  bring  forth  their 
young  soon  after  the  summer  solstice,  at  which  time 
they  abound  moct  in  a  crimson  juice,  which  even  now 
is  much  esteemed  and  employed  by  the  Turks  and  Ar- 
menians for  dyeing  wool,  silk,  and  hair,  and  also  to 
stain  the  nails  of  women's  fingers.  Wool  and  silk  were 
prepared  to  receive  this  dye  with  the  same  mordant  (of 
alum  and  tartar)  as  that  used  for  the  kermes.  Several 
writers  have  mentioned  the  coccus  polonicus  (sometimes 
called  the  cochineal  of  the  north);  but  the  best  account 
of  it  seems  to  be  that  given  by  Breynius  in  the  Act. 
Natur,  Curiosor.  of  the  year  1733.  There  is  also  an  ac- 
count of  it  in  the  Phil.  Trans,  for  1764,  p.  91.  Some 
writers  have  imagined,  that  the  Latin,  Italian,  and  French 
words,  signifying  crimson,  were  more  particularly  applied 
to  the  colour  dyed  from  the  coccus  polonicus;  but  I  do 
not  find  sufficient  reason  for  adopting  that  opinion. 

Very  similar  to  the  coccus  polonicus  is  an  insect, 
which  in  many  parts  of  Europe  was  formerly  collected 
from  the  roots  of  the  Burnet,  (poterium  sangui  sorba, 
Linn.);  and  which  was  used,  particularly  by  the  Moors, 


304  Philosophy  of  Permanent  Colours, 

for  dyeing  wool  and  silk  of  a  rose  colour.  Ray,  in  des- 
cribing this  plant,  says,  **  Hujus  radicis  adnascitur  qui- 
busdam  in  locis  granum  rubrum,  quo  utuntur  tinctorcs 
ad  colorem  carmesinum^  unde  sunt  qui  pro  cocco  habent, 
et  coccum  radicum  appellant,"  &c.  Hist.  Plantar.  401. 
The  coccus  uvae  ursi,  Linn.,  is  another  insect  of  the 
same  order,  and  very  much  resembling  the  coccus  polo- 
nicus,  both  in  its  properties  and  form,  excepting  the 
circumstance  of  its  being  nearly  twice  as  large.  It  affords 
9  crimson  dye  with  alum,  but  is  now  seldom  employed. 


Philosophy  of  Permanent  Colours,  305 

CHAPTER  III. 
Of  the  Natural  History  ofCochineaL 

"  Our  vallies  yield  not,  or  but  sparing  yield 

"  The  dyers*  gay  materials.  Only  weld, 

"  Or  root  of  madder,  here,  or  purple  woad, 

"  By  which  our  naked  ancestors  obscurM 

"  Their  hardy  limbs,  inwrought  with  mystic  forms, 

"  Like  Egypt's  obelisks." 

Dyer. 

ThiE  cochineal,  or  coccus  cacti  of  Linnaeus,  is  arrang- 
ed among  the  "  Insecta"  of  the  fifth  class  of  that  great 
naturalist;  and  in  the  second  order,  comprehending  the 
**  Hemiptera,"  (half-winged  insects,  &c.)  The  body  of 
the  male  is  slender,  of  a  red  colour,  covered  by  two 
wings,  spread  horizontally,  and  crossing  each  other  a 
little  on  the  back,  and  enabling  him  to  fly,  or  rather 
flutter.  The  head  is  distinct,  but  small,  with  two  diver- 
ging slender  antennas;  the  abdomen  or  tail  is  terminated 
by  two  small  and  very  long  diverging  hairs;  he  has  six 
feet,  with  which  he  sometimes  jumps,  like  the  lacca  in- 
sect; and  hence  Linnasus  has  applied  the  term  **  salta- 
toria,"  as  one  of  his  distinguishing  characters.  The  male 
insects  are  but  seldom  found  among  the  cochineal  sent 
to  Europe.  The  back  of  the  female  is  hemispherical,  and 
crossed  by  numerous  WTinkles;  she  is  of  a  dark  reddish 
brown  colour;  her  mouth  is  a  small  tubular  projection 
from  the  thorax;  she  is  without  wings,  but  has  six  legs; 
these,  however,  only  serve  her  to  remove  during  a  short 
interval  immediately  succeeding  her  birth;  after  which 
they  become  useless,  and  ceasing  to  grow,  whilst  the 
body  enlarges  greatly,  they,  with  the  proboscis  and  an- 
tennse,  remain  so  small  as  to  be  afterwards  hardly  percep- 
tible, at  least  without  a  very  minute  inspection.  This  cir- 
cumstance probably  occasioned,  and  certainly  confirmed. 

Vol.  L  2  Q 


306  Philosophy  of  Permanent  Colours. 

the  belief  which  prevailed  very  generally  in  Europe,  du- 
ring a  considerable  number  of  years,  that  these  insects 
were  vegetable  grains  or  seeds. ^ 

The  cochineal  is  nourished,  perhaps  exclusively,  by 
some  of  the  different  species  of  the  cactus,  or  Indian  fig, 
(called  by  some  of  the  prickly  pear,)  a  genus  of  plants, 
of  which  twenty-eight  several  species  have  been  descri- 
bed, all  originally  found  in  America  only;  of  very  differ- 
ent forms,  and  producing  fruits  of  various  colours  when 
ripe,  according  to  the  species  on  which  they  respectively 
grow,  as  yellow,  red,  crimson,  purple,  violet,  green,  &c. 
Among  these,  the  red  or  crimson- coloured  fruits  more 
especially  contain  a  mucilaginous  juice,  which  commu- 
nicates the  colour  of  the  fruit  in  a  high  degree  to  the 
urine  of  those  by  whom  it  is  eaten.  That  species  on  which 
the  domesticated  cochineal  has  been  commonly  propa- 
gated, is  denominated  cactus  cochenillifer  or  coccinilifer 
by  Linnaeus.  But  the  insects  live  naturally,  in  their  wild 
state  at  least,  on  some  of  the  other  species,  particularly 
the  cactus  tuna,  cactus  opuntia,  and  cactus  pereskia;  all 
of  which,  as  well  as  the  cactus  cochenillifer,  belong  to 

*  Caneparius  was  deceived  in  this  way.  He  had  been  informed, 
that  the  cochineal  consisted  of  insects  collected  from  plants  of  the 
cactus  kind  by  the  help  of  forceps,  and  smotheredi  but  he  considered 
this  as  fabulous,  asserting  that  the  cochineal,  which  he  calls  "  ka- 
basinii  grana"  if  steeped  in  hot  water,  recovered  their  originalform^ 
which,  adds  he,  is  not  that  of  any  thing  animalcular,  but  distinctly 
the  figure  of  a  seed  or  grain  of  some  fruit.  "  Non  est  ullius  anima- 
lunculi,  at  seminis  sive  grani  fructus  figuram  refert.  Quare  haec 
grana  sunt  ficus  Indicae  rubra  et  splendida  ut  sanguis."  He  had 
heard  that  the  fruit  of  the  cactus  "  Tuna,'*  or  Indian  fig,  was  red, 
and  that  it  tinged  the  urine  of  those  eating  it,  of  a  blood  colour, 
which  encouraged  him  to  conclude  as  he  did,  that  cochineal  must 
be  the  seeds  "  i/isius  iuna;"-—^^  pro  colore,  carbisino  vulgo  chremise 
conficiendo  tinctoribus  commodo."  See  Caneparius,  De  Atramentis, 
&c.  Venice,  1619,  p,  211,212. 


Philosophy  of  Permanent  Colours.  307 

that  section  of  cacti  which  Linn^us  distinguishes  as 
"  opuntias  compressae,  articulis  proliferis,"  i,  e.  flattened 
or  compressed  with  prolific  articulations.  The  cactus  co- 
chenillifer,  however,  which  the  Mexican  Spaniards  call 
nopal,  is  alone  cultivated  for  the  purpose  of  feeding  and 
breeding  these  insects;  partly  because  is  is  unarmed,  or 
without  those  offensive  spines  which  beset  most  of  the 
other  species. 

The  Spaniards,  on  their  first  arrival  in  Mexico,  about 
the  year  1518,  saw  the  cochineal  employed,  (as  it  ap- 
pears to  have  been  long  before,)  by  the  native  inha- 
bitants of  that  coimtry,  in  colouring  some  parts  of 
their  habitations,  ornaments,  &c.  and  in  staining  their 
cotton;  and  being  struck  with  its  beautiful  colour,  some 
accounts  of  it  were  given  to  the  Spanish  ministry,  who 
in  the  year  1523,  (as  Herrara  informs  us)  ordered  Cortes 
to  take  measures  for  multiplying  this  valuable  commo- 
dity;* but  as  the  Spaniards  then  in  America  were  care- 
less  of  every  thing  but  gold  and  silver,  they  left  this  to 
be  done  by  the  natives,  who,  from  the  large  supplies 
soon  after  sent  to  Europe,  appear  to  have  successfully 
employed  themselves  for  that  purpose. 

It  is  remarkable,  that  though  Acosta  had  stated  the 
cochineal  to  be  an  insect,  as  early  as  1530,  and  though 

♦  Herrara  does  not  use  the  name  of  cochineal,  but  that  of  grana^ 
(as  other  Spanish  writers  have  since  done);  and  he  says,  (Decade, 
iii.  V.  3.)  the  Catholic  King  had  been  informed  that  these  grana 
were  abundant  in  that  part  of  America,  and  that  the  sending  them 
to  Spain  might  furnish  means  for  paying  the  contributiojis^  Sec: — 
they  were  probably  then  supposed  to  resemble  kermes.  I  have  not 
been  able  to  ascertain  the  origin  of  the  term  cochineal,  or  cocci- 
nilla,  nor  the  time  when  it  was  first  applied  to  these  insects:  per- 
haps, as  they  were  smaller  than  the  kermes,  the  term  coccinilla 
was  intended  as  a  diminutive  of  coccumy  as  platina  was  of  Plata,  and 
both  employed  from  similar  motives;  perhaps,  also,  it  may  have 
been  erroneously  supposed  to  belong  to  the  genus  coccinilla,  oi: 
lady-bird. 


308  Philosophy  of  Permaneftt  Colours. 

Herrara  and  Hernandez  did  the  same  afterwards,  these 
opinions  were  generally  overlooked  or  disregarded,  and 
the  people  of  Europe  were  for  many  years  induced  to 
believe,  that  this  insect  was  a  vegetable  grain  or  seed, 
as  I  lately  mentioned;  a  contrary  opinion  was,  indeed, 
given  by  the  anonymous  author  of  a  paper,  in  the  third 
volume  of  the  Philosophical  Transactions,  (printed  in 
the  year  1668,)  in  which  he  supposes  cochineal  to  be 
an  insect,  "  engendered^^  by  the  fruit  of  the  prickly  pear; 
and  being  a  believer  of  equivocal  generation,  he  pro- 
poses to  employ  fermentation  as  a  means  of  engendering 
and  multiplying  these  insects  more  copiously. 

In  the  year  1672,  a  paper  written  by  Lister,  was  pub- 
lished in  the  seventh  volume  of  the  Philosophical  Trans- 
actions, concerning  the  kermes,  in  which  he  '*  conjec- 
tures cochineal  may  be  a  sort  of  kermes."  And  the 
seventeenth  volume  of  the  Transactions,  published  in 
1691,  contains  some  observations  concerning  the  mak- 
ing of  cochineal  according  to  a  relation  had  from  an  old 
Spaniard  at  Jamaica,  who  says,  "  Cochineal  is  the  same 
which  we  call  lady-bird,  alias  cow-lady,*  which  at  first 
appears  like  a  small  blister,  or  little  knob  upon  the  leaves 
of  the  shrub  on  which  they  breed,  and  which  afterwards, 
by  the  heat  of  the  sun,  becomes  a  live  insect  as  above, 
or  a  small  grub." 

Early  in  1693,  Father  Plumier  wrote  and  subscribed 
a  declaration,  which  he  delivered  to  Pomet,  affirming 
cochineal  to  be  an  insect  living  on  the  opuntia  or  Indian 
fig,  and  that  he  had  seen  it  in  the  island  of  St.  Domingo; 

*  The  lady-bird,  or  cow-lady,  has  long  been  distinguished  by  the 
generic  name  oi  coccinella;  a  fact  which  may  have  occasioned  seve- 
ral mistakes.  It  seems  to  have  misled  Professor  Fischer,  when,  in 
1758,  he  proposed  to  propagate  the  lady-bird  or  fly,  by  placing  it 
on  the  kermes  oak,  and  the  perennial  knawel,  in  order  to  produce 
cochineal  in  Europe. 


Philosophy  of  Permanent  Colours,  309 

and  De  Laet  had  some  little  time  before  described  it  as 
feeding  on  the  tuna.  Pomet,  however,  misled  by  the 
prevailing  opinion  on  this  subject,  as  well  as  by  several 
letters  which  about  that  time  were  sent  to  him  from  St. 
Domingo  by  F.  Rousseau,  adopted  the  fallacious  ac- 
counts of  this  letter- writer,  (who  promised  to  send  over 
to  France  some  of  the  very  plants  whose  seeds,  as  he 
asserted,  afforded  the  true  cochineal,)  and  described 
this  drug  as  the  seed  oi  a  plant,  two  or  three  feet  high, 
bearing  pods  of  a  conical  form,  in  which  the  cochineal 
grew  naturally.  (See  Hist.  Gen.  des  Drogu  s,  &c.) 

But,  groundless  as  this  account  was  in  reality,  it  ob- 
tained so  much  credit,  that  no  longer  than  four  years 
since,  a  very  eminent  dyer  of  this  metropolis  seriously 
told  me,  that  having  bought  a  large  parcel  of  cochineal, 
he  actually  found  among  it  one  of  these  conical  pods, 
containing  cochineal  naturally  attached  to  the  inside  of 
the  pods. 

Lewenhoek,  however,  by  his  glasses  plainly  saw,  that 
the  cochineal  was  an  insect  with  six  legs;  and  in  a  letter, 
read  at  the  Royal  Society  the  21st  of  March,  1704,  and 
published  in  the  24th  volume  of  the  Transactions,  he 
positively  contradicted  all  those  who  had  represented  it 
as  a  vegetable  grain;  and  declared  that,  by  dissections, 
he  had  invariably  found  eggs,  or  animalcula,  in  the  sup- 
posed grains,  and  often  to  the  amount  of  two  hundred 
in  each.  He  also  represents  these  insects  as  "  not  pro- 
duced from  worms,"  but  as  "  at  once  bringing  forth 
their  like." 

About  the  year  1730,  Dr.  Rutty,  then  Secretary  of  the 
Royal  Society,  published  a  Natural  History  of  Cochi- 
neal, (in  the  36th  volume  of  the  Transactions,)  from  a 
work  on  this  subject  by  Melchior  de  la  Ruuscher,  of 
Amsterdam,  who  had  procured  from  Antiquera,  in  New 
Spain,  the  depositions  of  eight  persons,  who  had  been 


310  Philosophy  of  Permanent  Colours, 

actually  employed  for  many  years  in  the  breeding  and 
management  of  cochineal,  and  who  swore  that  they 
were  small  living  animals  with  "  a  beak,  eyes,  feet," 
&c.;  and  the  originals  of  these  depositions,  notarially 
authenticated,  were  deposited  in  the  archives  of  the 
Royal  Society.*  Not  long  after  this,  Reaumur,  in  his 
Hist,  des  Insectes,  and  Dr.  Brown,  in  his  History  of 
Jamaica,  described  the  female  cochineal  with  sufficient 
accuracy;  as  did  Linnaeus  some  time  after,  from  some 
■which  had  been  sent  to  him  by  Rolander  from  Surinam, 
in  the  year  1756;t  though  neither  of  these  naturalists 
had  ever  seen  the  male  cochineal. 

About  the  beginning  of  the  year  1757,  the  late  John 
Ellis,  Esq.  F.  R.  S.,  hearing  that  the  cochineal  insect 
bred  in  great  abundance  on  the  cactus  opuntia,  in  South 
Carolina  and  Georgia,  wrote  to  Dr.  Alexander  Garden, 
of  Charleston,  South  Carolina,  for  some  of  the  joints 
of  that  plant,  with  the  insects  thereon,  which  were  ac- 
cordingly sent  the  latter  end  of  that  year,  and  laid  be- 
fore the  Royal  Society.  "  These  specimens  (says  Mr. 
Ellis)  were  full  of  the  nests  of  this  insect,  in  which  it 

*  These  depositions  were  juridically  taken  in  October,  1725,  to 
decide  a  wager  on  this  subject,  which  wager  is  said  to  have  amount- 
ed to  the  whole  fortune  of  the  loser,  though  the  greater  part  of  it 
was  afterwards  generously  restored,  after  having  been  paid.  De  la 
Ruuscher's  publication  was  intitled,  "  Naturlyke  historic  van  de 
couchenille,  beweezen  met  authentique  documenten;"  printed  at 
Amsterdam,  by  Hermanns  Uytwerf,  1729. 

t  Rolander  had  been  one  of  Linnaeus's  pupils,  and  having  sent 
to  the  latter  a  cactus^  stocked  with  the  ivild  cochineal  insects,  (there 
being  no  other  at  Surinam),  the  plant  was  brought  to  Upsal  whilst 
the  Professor  was  delivering  a  lecture,  and  when  he  afterwards  in- 
quired for  it,  the  gardener  told  him,  he  just  cleaned  away  the  ver- 
min^ which  he  supposed  the  cochineal  to  be,  and  had  planted  it. 
And  as  none  of  the  insects  could  be  found  alive,  Linnaeus's  descrip- 
tion must  have  been  made  from  those  which  were  dead. 


Philosophy  of  Permanent  Colours.  311 

appeared  in  its  various  states,  from  the  most  minute, 
when  it  walks  about,  to  the  state  when  it  becomes  fixed 
and  wrapt  up  in  a  fine  web,  which  it  spins  about  itself. 

"  In  order  to  find  out  the  male  fly,  (continues  he,)  I 
examined  all  the  webs  in  these  specimens,  besides  a 
large  parcel  which  the  Doctor  had  sent  me  picked  oiF 
from  the  plants  in  Carolina,  and  at  last  discovered  three 
or  four  minute  dead  flies  with  white  wings.  These  I 
moistened  in  weak  spirit  of  wine,  and  examining  them 
in  the  microscope,  I  discovered  their  bodies  to  be  of  a 
bright  red  colour,  which  convinced  me  of  their  being 
the  true  male  insect.  To  be  confirmed  in  my  opinion,  I 
immediately  communicated  my  discovery  to  Dr.  Gar- 
den, which  I  accompanied  with  an  exact  microscopical 
drawing,  and  desired  he  would  send  me  some  account 
of  their  economy,  with  some  male  insects  of  his  own 
collecting;  which  he  did,  in  the  spring  of  the  year  1762, 
accompanied  with  the  following  observations: 

"In  August  1759,  (says  Dr.  Garden),  I  catched  a 
male  cochineal  fly,  and  examined  it  in  your  aquatic 
microscope.  It  is  seldom  a  male  is  met  with.  I  imagine 
there  may  be  one  hundred  and  fifty  or  two  hundred 
females  for  one  male.  The  male  is  a  very  active  crea- 
ture, and  well  made,  but  slender  in  comparison  of  the 
females,  who  are  much  larger  and  more  shapeless,  and 
seemingly  lazy,  torpid,  and  inactive.  They  appear  ge- 
nerally so  overgrown,  that  their  eyes  and  mouth  arc 
quite  sunk  in  their  rugas  or  wrinkles;  nay,  their  antennaj 
and  legs  are  almost  covered  by  them,  and  are  so  im- 
peded in  their  motions  from  these  swellings  about  the 
insertions  of  their  legs,  that  they  can  scarce  move  them, 
much  less  move  themselves. 

"  The  male's  head  is  very  distinct  from  the  neck:  the 
neck  is  much  smaller  than  the  head,  and  much  more  so 
than  the  body.  The  thorax  is  elliptical,  and  something 


312  Philosophy  of  Permanent  Colours* 

larger  than  the  head  and  neck  together,  and  flattish  un- 
derneath; from  the  front  there  arise  two  antennae,  (much 
longer  than  those  of  the  females),  which  the  insect 
moves  every  way  very  briskly.  These  antennae  are  all 
jointed,  and  from  every  joint  there  come  out  four  short 
setae,  placed  two  on  each  side. 

"  It  has  three  jointed  legs  on  each  side,  and  moves 
very  briskly  and  with  great  speed.  From  the  extremity 
of  the  tail,  there  arise  two  long  setae  or  hairs,  four  or  five 
times  the  length  of  the  insect.  They  diverge  as  they 
lengthen,  are  very  slender,  and  of  a  pure  snow-white 
colour.  It  has  two  wings,  which  take  their  rise  from  the 
back  part  of  their  shoulders  or  thorax,  and  lie  down  ho- 
rizontally, like  the  wings  of  the  common  fly,  when  the  in- 
sect is  walking.  They  are  oblong,  rounded  at  the  extre- 
mity, and  become  suddenly  small  near  the  point  of  in- 
sertion. They  are  much  longer  than  the  body,  and  have 
two  long  nerves;  one  runs  from  the  basis  of  the  wing 
along  the  external  margin,  and  arches  to  meet  a  slender 
one  that  runs  along  the  under  and  inner  edge.  They  are 
quite  thin,  slender,  transparent,  and  of  a  snowy  white- 
ness. The  body  of  the  male  is  of  a  lighter  red  than  the 
body  of  the  female,  and  not  near  so  large."* 

To  Dr.  Garden's  description,  Mr.  Ellis,  in  an  account 
of  the  male  and  female  cochineal  insects,  accompanied 
with  drawings,  &c.  (in  the  fifty-second  volume  of  the 
Philosophical  Transactions,)  adds,  that  the  female  has  a 

*  Justice  to  Mr.  Catesby,  requires  me  to  mention  that  he  had 
some  years  before  published  the  following  statement  in  the  Intro- 
duction to  the  first  volume  of  his  Natural  History  of  Carolina,  &c. 
viz.  "  In  South  Carolina  grows  a  kind  of  Opuntia,  which  are  fre- 
quently three  or  four  feet  high,  from  which  I  have  often  flicked 
cochineal  in  small  quantities.  Both  plants  and  insects  were  much 
smaller  than  those  of  Mexico;  but  the  latter  (i.  c.  the  insects)  were 
in  colour  and  appearance  the  same." 


Philosophy  of  Permanent  Colours.  313 

remarkable  proboscis,  or  awl- shaped  papilla,  arising  in 
the  midst  of  the  breast,  which  Linnaeus  calls  the  ros- 
trum, and  thinks  it  the  mouth:  "  if  so,  (says  Mr.  Ellis,) 
besides  the  office  of  supplying  it  with  nourishment  dur- 
ing the  time  of  its  moving  about,  it  is  the  tube  through 
which  the  fine  double  filament  proceeds,  with  which 
it  forms  its  delicate  web,  in  order  to  accommodate 
itself  in  its  torpid  state,  during  its  pregnancy,  till  the 
young  ones  creep  out  of  its  body,  shift  for  themselves, 
and  form  a  new  generation. 

"  In  this  torpid  state  the  legs  and  antennas  grow  no 
more,  but  the  animal  swells  up  to  an  enormous  size,  in 
proportion  to  its  minute  creeping  state.  The  legs,  an- 
tennae, and  proboscis,  are  so  small  with  respect  to  the 
rest  of  the  body,  that  they  cannot  be  easily  discovered, 
without  very  good  eyes  or  magnifying  glasses,  so  that  to 
an  indifferent  eye  it  looks  full  as  much  like  a  berry  as  an 
animal. 

"  As  soon  as  the  female  is  delivered  of  its  numerous 
progeny,  it  becomes  a  mere  husk  and  dies;  so  that  great 
care  is  taken  in  Mexico,  where  it  is  principally  collected, 
to  kill  the  old  ones  while  big  with  young,  to  prevent 
the  young  ones  escaping  into  life,  and  depriving  them 
of  that  beautiful  scarlet  dye,  so  much  esteemed  by  all 
the  world." 

I  ought  to  have  sooner  mentioned  that  there  are  two 
sorts  or  varieties  of  cochineal;  the  best  or  domesticated, 
which  the  Spaniards  denominate  ^rawc^wc,  or  fine  grain; 
and  the  wild,  which  they  call  grana  sylvestra.  The  for- 
mer is  nearly  twice  as  large  as  the  latter;  probably  be- 
cause its  size  has  been  improved  by  the  favourable  ef- 
fects of  human  care,  and  of  a  more  copious  or  suitable 
nourishment,  derived  solely  from  the  cactus  cochenillifer, 
during  many  generations.  But  it  is  only  from  the  wild 
cochineal,  living  naturally  on  some  of  the  opunti^e,  in 

Vol.  I.        '  2  R 


314  Philosophy  of  Permanent  Colours. 

different  parts  of  America,  that  the  descriptions  of 
Brown,  Linnaeus,  and  Ellis,  were  taken.  It  must  also 
be  observed,  that  the  grana  sylvestra  are  not  only  smaller 
than  the  others,  but  that  their  bodies  are  covered  by  very 
fine  white  downy  filamenu,  which  they  spin  to  defend 
themselves  against  cold,  rain,  &c.  in  their  wild  state; 
but  which  adding  to  their  weight,  whilst  it  yields  no  co- 
lour, contributes  with  other  causes  to  render  them  less 
valuable. 

In  the  month  of  January,  1777,  Mons.  ThierJ''  de  Me- 
nonville  left  Port-au-Prince,  in  the  Island  of  St.  Do- 
mingo, for  the  purpose  of  procuring  some  of  the  living 
cochineal  insects  in  Mexico,  and  bringing  them  away,  to 
be  afterwards  propagated  in  the  French  West  India 
islands:  an  enterprise,  for  the  expense  of  which  four 
thousand  livres  had  been  allotted  by  the  French  govern- 
ment. He  proceeded  by  the  Havannah  to  La  Vera  Cruz, 
and  was  there  informed  that  the  finest  cochineal  in- 
sects were  produced  at  Guaxaca,  distant  about  seventy 
leagues.  Pretending  ill  health,  he  obtained  permission  to 
use  the  baths  of  the  river  Magdalena;  but  instead  of 
going  thither,  he  proceeded  through  various  difiiculties 
and  dangers,  as  fast  as  possible,  to  Guaxaca,  where, 
after  making  his  observations,  and  obtaining  the  requi- 
site information,  he  affected  to  believe  that  the  cochineal 
insects  were  highly  useful  in  composing  an  ointment  for 
his  pretended  disorder  (the  gout),  and  therefore  pur- 
chased a  quantity  of  nopals,  covered  with  these  insects, 
of  the  fine  or  domestic  breed,  and  putting  them  into 
boxes  with  other  plants,  for  theif  better  concealment,  he 
found  means  to  get  them  away  as  botanic  trifles,  un- 
worthy of  notice,  notwithstanding  the  prohibitions  by 
which  the  Spanish  government  had  endeavoured  to 
hinder  their  exportation;  and  being  afterwards  driven 
by  a  violent  storm  into  the  bay  of  Campeachy,  he  there 


Philosophy  of  Permanent  Colours.  315 

found  and  added  to  his  collection  a  living  cactus,  of  a 
species  which  was  capable  of  nourishing  the  fine  domes- 
ticated cochineal;  after  which,  departing  for  St.  Do- 
mingo, he  arrived  safe  with  his  acquisitions,  on  the 
25th  of  September,  (in  the  same  year,)  at  Port-au- 
Prince,  where  he  began  immediately  to  form  a  planta- 
tion of  nopals,  and  to  take  steps  for  propagating  the 
two  sorts  or  varieties  of  cochineal;  I  mean  the  domesti- 
cated or  fine,  and  the  sylvestra  or  wild;  .which  last  he 
found  at  St.  Domingo,  soon  after  his  return,  living  na- 
turally on  the  cactus  pereskia.  But  unfortunately  for  this 
establishment,  he  died  in  the  year  1780,  through  disap- 
pointment and  vexation,  at  seeing  his  patriotic  endea- 
vours so  little  assisted,  and  his  services  so  sparingly  re- 
warded by  the  government.  M.  Thiery  de  Menonville's 
labours  being  thus  thus  terminated,  the  Royal  Society  of 
Arts  and  Sciences  at  Cape  Frangois,  having  collected  his 
papers,  composed  from  them  a  treatise  on  the  cultiva- 
tion of  the  nopals,  and  the  breeding  of  cochineal,  &c.  of 
which  M.  Berthollet  has  given  a  short  extract  in  the  fifth 
volume  of  the  Annales  de  Chimie,  together  with  an  ac- 
count of  his  own  experiments  for  ascertaining  the  effects 
of  the  grana  sylvestra,  produced  at  St.  Domingo,  com- 
pared with  those  from  Mexico,  in  dyeing.^ 

From  the  observations  of  M.  Thiery  de  Menonville, 
it  appears  that  there  are  two  varieties  of  the  nopal,  or 
cactus  cochenillifer,  growing  in  Mexico,  one  called  the 
true  nopal  of  the  Garden  of  Mexico,  and  the  other  the 
Castilian  nopal,  a  name  given  to  the  last  of  these  varieties 
on  account  of  its  singular  beauty.  It  appears  also  that 
the  wild  cochineal,  or  grana  sylvestra,  when  reared  upon 

*  The  original  publication  (from  which  my  account  was  writ- 
ten,) is  entitled,  "  Traite  de  la  Culture  du  Nopal  et  de  TEduca- 
tion  de  la  Cochenille,"  8vo.  printed  at  Cape  Fran9ois,  1787. 


316  Philosophy  of  Permanent  Colours, 

either  of  these  varieties  of  the  nopal,  become  almost  as 
large  as  the  fme  or  domesticated  sort,  and  lose  the 
greatest  part  of  those  fine  downy  filaments  with  which 
they  are  naturally  covered,  and  which  contribute  to  ren- 
der them  less  valuable  than  the  latter. 

But  besides  the  advantage  of  affording  the  most  suit- 
able nourishment  to  cochineal,  the  nopals  have  another 
of  very  great  importance,  where  these  insects  are  to  be 
raised  as  objects  of  commerce;  which  is,  that  they  are 
not  beset  with  thorns  or  prickles,  like  most  of  the  cacti, 
and  particularly  the  opuntia,  tuna,  and  pereskia,  which, 
by  this  circumstance,  render  the  insects  nourished  upon 
them,  almost  inaccessible  to  any  who  might  wish  to  col- 
lect them:  whilst  the  true  nopal,  and  that  of  Castile,  have 
none  but  soft  inoffensive  thorns,  and  the  nourishment 
which  they  afford  is  at  the  same  time  so  peculiarly  well 
suited  to  the  cochineal,  and  especially  to  the  fine  or 
domesticated  sort,  that  these  last,  though  they  can  sub- 
sist on  some,  will  prosper  on  no  other  species  of  cactus; 
and  indeed  the  wild  sort,  though  found  naturally  upon 
several  other  species  of  opuntia,  are  at  present  raised 
chiefly  on  the  nopals  in  Mexico.  The  young  insects, 
whilst  contained  within  the  mother,  appear  to  be  all 
connected  one  after  the  other  by  an  umbilical  cord  to 
a  common  placenta,  and  in  this  order  they  are  in  due 
time  brought  forth  as  living  animals,  after  breaking 
the  membrane,  in  which  they  were  at  first  probably 
contained  as  eggs.  Being  thus  brought  forth,  they  re- 
main in  a  cluster  under  the  mother's  belly  for  two  or 
three  days,  until  disengaged  from  the  umbilical  cord; 
after  which  the  females,  for  the  only  time  of  their  lives, 
exercise  their  loco-motive  faculties,  by  creeping  to  pro- 
per situations  on  the  plant;  and  in  doing  this  they  are 
led  by  a  wise  instinct,  to  prefer  the  undersides  of  the 
different  branches  or  articulations,  (as  being  most  de- 


Philosophy  of  Permanent  Colours.  317 

fended  from  wind  and  rain,)  where  each  attaches  herself, 
by  inserting  her  Httle  tubular  proboscis  or  mouth  into 
the  bark,  and  thus  remain  fixed  to  the  end  of  life.  By 
this  insertion  the  female  draws  out  for  her  nourishment 
the  colourless  mucilaginous  juice  of  the  nopal,  and  soon 
becomes  covered  with  a  fine  adhesive  downy  substance. 
The  male  acquires  a  similar  covering,  but  quits  it  at  the 
end  of  a  month,  and  in  the  shape  of  a  little  scarlet  fly, 
jumps  and  flutters  about  for  the  purpose  of  copulation; 
and  having  thereby  secured  a  future  progeny,  he  dies 
almost  immediately  after.  But  the  female  having  other 
duties  to  perform,  outlives  the  male  another  month;  at 
the  end  of  which  she  is  ready  to  bring  forth  her  young, 
and  this  is  the  precise  time  for  gathering  those  which 
are  not  wanted  for  breeding;  which  is  done  by  pressing 
the  dull  blade  of  a  knife  between  the  under  surface  of  a 
branch  of  the  nopal,  and  the  clusters  of  insects  attached 
to  it,  when  the  latter,  being  thereby  separated,  fall  upon 
cloths  previously  spread  on  the  ground  to  receive  them; 
and  a  sufficient  quantity  being  thus  collected,  they  are 
dipped  (enclosed  in  a  linen  cloth  or  bag)  into  boiling 
water,  and  suffered  to  remain  in  it  so  long  as  is  neces- 
sary for  killing  them,  but  no  longer,  lest  the  water 
should  extract  some  of  their  colour.  This  being  done, 
they  are  thoroughly  dried,  by  spreading  and  exposing 
them  to  the  rays  of  the  sun,  by  which  they  shrink  so 
as  generally  to  lose  about  two-thirds  of  their  former 
weight.  This,  which  has  been  found  to  be  the  best 
method  of  drying  the  cochineal,  is  now  generally  prac- 
tised, though  others  were  formerly  in  use;  such  as  ovens, 
flat  baking  stones  heated,  &c. 

M.  Thiery  de  Menonville  describes  the  male  of  the 
domesticated  or  fine  cochineal  as  perfectly  similar  to 
that  of  the  wild  in  every  respect,  excepting  its  size;  nor 
does  there  appear  to  be  any  considerable  difference  be- 


318  Philosophy  of  Permanent  Colours. 

tween  the  females  of  these  two  varieties.  The  domesti- 
cated female,  instead  of  that  downy  covering,  which 
enables  the  wild  to  bear  inclement  seasons,  is  only  co- 
vered by  a  fine  white  powder  or  farina,  serving  in  some 
degree  as  a  defence  against  rain  and  cold,  but  not  enough 
to  enable  her  to  remain  abroad  like  the  wild  insects  du- 
ring the  rainy  seasons,  which  occur  twice  in  every  year. 
When  these  approach,  the  domesticated  insects  are  all 
gathered  and  dried,  excepting  only  those  intended  for 
breeding  a  future  stock;  which  are  preserved,  by  either 
removing  the  nopals  inhabited  by  them,  into  situations 
where  they  are  secured  from  wind  and  rain,  or  by  rais- 
ing frames  over  them,  and  covering  them  with  thatch 
or  matting,  until  the  return  of  favourable  weather;  but 
the  wild  insects,  being  more  hardy,  as  well  as  more  pro- 
lific, when  once  placed  upon  the  nopals,  would  not  only 
perpetuate,  but  multiply  themselves,  without  any  farther 
care,  to  such  a  degree  as  to  exhaust  and  destroy  the 
plants,  were  they  not  all  collected  at  the  end  of  every  two 
months,  and  the  plants  perfectly  cleansed  (by  wiping  them 
with  wetted  cloths)  from  the  down  and  other  animal 
impurities  left  on  their  branches.  The  nopals  become 
fit  to  nourish  the  cochineal  at  the  end  of  eighteen  months 
from  the  time  they  were  planted.  The  quantity  of  fine 
or  domesticated  cochineal,  which  a  single  nopal  can 
nourish,  usually  weighs  a  third  more  than  it  could  nou« 
rish  of  the  wild.  These  last  have  also  the  disadvantage 
of  selling  for  a  much  less  price;  but  in  return,  they  are 
gathered  six  times  in  each  year,  whilst  the  fine  yield 
but  three  crops  in  the  same  space,  their  propagation 
being  wholly  suspended  during  the  rainy  seasons. 

In  Mexico  it  is  thought  necessary  to  keep  the  two 
sorts  or  varieties  of  cochineal  separated,  at  the  distance 
of  about  one  hundred  perches  from  each  other,  lest  the 
males  of  the  wild,  by  impregnating  the  females  of  the 


Philosophy  of  Permanent  Colours.  319 

other  sort,  should  occasion  a  degeneration  of  the  latter; 
a  circumstance  which  seems  to  indicate  that  both  sorts 
originated  from  the  same  stock,  and  that  the  domesticat- 
ed is  only  an  amelioration  of  the  wild  cochineal,  through 
the  fiwourable  effects  of  a  more  suitable  nourishment, 
and  of  warm  covering;  and  this  is  rendered  the  more 
probable,  by  M.  Thiery  de  Menonville's  observation, 
that  the  former  are  never  found  in  the  fields  or  forests 
of  Mexico,  nor  indeed  any  where  but  in  the  gardoiis 
and  plantations  of  those  employed  in  rearing  them.  But 
if  the  present  size,  appearance,  and  habits,  of  the  do- 
mestic cochineal,  were  those  which  naturally  belong  to 
the  insect,  it  might  be  supposed  capable  of  maintaining 
an  independent  existence,  remote  from  the  dwellings, 
and  without  the  help  of  mankind,  as  it  must  have  done 
before  its  properties  were  so  well  known  as  to  render  it 
an  object  of  human  care  and  protection;  and  in  that  case, 
some  of  this  sort  of  cochineal  doubtless  would  have  con- 
tinued to  subsist  in  their  natural  state,  since  the  whole 
of  a  race,  composed  of  so  many  minute  individuals, 
could  not  have  been  taken  and  brought  under  the  pro- 
tection and  dominion  of  man.  Nor  is  it  easy  to  explain 
why  none  of  them  ever  are  found  in  a  wild  state,  but 
by  supposing  them  to  have  been  rendered  efteminate 
by  luxurious  food,  and  by  protection  from  inclement 
weather;  and  that,  consequently,  they  have  been  enabled 
to  lay  aside  their  natural  downy  clothing,  as  sheep  lay 
aside  their  wool,  when,  after  being  removed  to  warm  cli- 
mates, they  find  it  no  longer  necessary;  and  that  their 
natural  habits  and  means  of  self-preservation  being  lost, 
they  are  rendered  incapable  of  subsisting  without  a  con- 
tinuance of  the  same  fostering  cart  which  first  occasion- 
ed their  effeminacy;  or,  if  they  ever  do  find  means  to 
subsist  without  it,  they  do  so  only  by  regaining  their 
natural  downy  covering,  and  by  returning  again  to  their 


320  Philosophy  of  Permanent  Colours, 

primitive  habits,  so  as  not  to  be  any  longer  distinguish- 
able from  those  who  were  never  out  of  the  wild  state. 

After  the  death  of  M.  Thiery  de  Menonville,  the 
stock  of  fine  or  domesticated  cochineal,  which  he  had 
multiplied  in  the  garden  at  Port-au-Prince,  was  suffered 
to  perish  by  neglect;  but  the  hardier  wild  sort,  having 
found  means  to  subsist,  though  neglected,  was  after- 
wards taken  under  the  care  of  M.  Bruley,  (substitute 
of  the  attorney -general  of  that  province,)  who  from  the 
remains  of  M.  de  Menonville's  establishment,  formed 
a  plantation  for  propagating  and  multiplying  these  in- 
sects, of  which  he  sent  a  considerable  quantity,  in  the 
year  1787,  to  the  minister  of  the  French  marine  at  Paris, 
at  whose  request  the  Royal  Academy  of  Sciences  com- 
missioned M.  Berthollet,  and  three  others  <3f  its  members, 
to  cause  proper  experiments  to  be  made  therewith,  which 
they  accordingly  did,  under  their  own  inspection,  at  the 
celebrated  establishment  of  the  Gobelins  near  Paris;  and 
from  these  experiments  it  appeared,  that  the  grana  syl- 
vestra  of  St.  Domingo  afforded  colours  by  dyeing,  ex- 
actly similar  to  those  of  the  Spanish  fine  cochineal, 
allowing  only  after  the  rate  of  twelve  ounces  of  the  for- 
mer for  five  of  the  latter.  M.  Bruley  some  time  after 
sent  to  France  a  second  parcel  of  the  same  cochineal, 
produced  from  his  plantation  in  the  year  1788;  and  this 
being  tried  by  the  same  commissaries  of  the  Royal 
Academy,  though  in  different  ways,  produced  nearly 
the  same  effects. 

Very  considerable  differences  of  external  colour  or 
appearance  occur  in  different  parcels  of  the  fine  cochi- 
neal; probably,  because  the  white  farinaceous  powder, 
with  which  these  insects  are  naturally  covered,  is  more 
or  less  washed  off  by  the  hot  water  in  which  they  are 
killed  by  immersion,  as  well  as  by  other  circumstances 
which  occur  in  the  drying  and  packing.  When  this 


Philosophy  of  Permanent  Colours,  321 

powder  has  been  entirely  removed,  the  insects  appear 
of  a  chocolate  colour,  inclining  a  little  to  the  purple, 
and  they  are  then  called  renigrida.  Generally,  however, 
so  much  of  the  white  powder  remains,  especially  in  the 
little  furrows  which  cross  the  insect's  back,  as  occasions 
a  greyish  appearance,  called  jospeada;  and  sometimes, 
indeed,  this  powder  so  perfectly  covers  the  cochineal, 
as  to  render  them  all  over  white.  This  I  remember  to 
have  been  particularly  the  case  with  a  parcel  which  a 
friend  of  mine  had  purchased,  and  which  was  refused 
by  several  dyers  to  whom  it  had  been  sent,  from  a  per- 
suasion of  its  having  been  fraudulently  covered  by  white 
lead,  or  some  other  metallic  calx  intermixed  with  it,  to 
increase  the  weight;  and  one  very  eminent  dyer  alleged, 
that  he  had  formerly  seen  and  tried  a  similar  parcel,  and 
that  the  white  powder  had  been  found  to  consist  princi- 
pally of  a  preparation  of  mercury.  That  I  might  be  en- 
abled to  ascertain  whether  an  opinion  so  unlikely  had 
any  foundation,  my  friend  caused  several  ounces  of  this 
powder  to  be  separated  from  the  insects  by  sifting;  and 
having  tried  it  sufficiently,  I  found  it  to  be  entirely  of 
an  animal  nature,  and  apparently  nothing  but  the  farina 
which  naturally  covers  these  insects.  It  even  yielded  a 
considerable  portion  of  the  true  cochineal  colour,  and 
dyed  good  scarlets  in  the  usual  way,  though  it  probably 
was  assisted  by  some  of  the  limbs  or  other  parts  of  the 
bodies  of  the  insects,  separated  by  rubbing  in  the  sieve: 
but  I  am  persuaded  that  a  part  of  the  colour  in  question 
naturally  existed  in  the  farina  or  white  powder  itself; 
and  if  this  be  the  case,  it  would  be  highly  advantageous 
to  contrive  means  for  killing  the  cochineal,  without 
washing  off  any  part  of  the  powder  in  question,  which 
might,  I  think,  be  done  by  putting  them  into  tinned 
vessels,  made  so  as  to  shut  closely,  which  might  be 
plunged  into  boiling  water,  and  withdrawn  at  a  proper 
Vol.  I.  2  S 


322  Philosophy  of  Permanent  Colours. 

time,  without  letting  a  single  drop  of  water  come  into 
contact  with  the  insects,  or  carrying  off  any  of  the  pow- 
der in  question.  And  perhaps  this  method  might  be  used 
with  advantage,  even  if  it  should  be  found  that  no  colour- 
ing matter  resides  in  the  white  powder,  since  it  is  difficult 
to  conceive  that  the  cochineal  can  be  plunged  into  boil- 
ing water,  so  as  to  wash  away  the  powder  entirely,  (as 
is  frequently  done,)  without  a  loss  of  some  part  of  the 
colouring  matter  contained  in  the  bodies  of  the  insects 
themselves.  In  general,  therefore,  it  will  be  safest  to 
choose  that  cochineal  which  is  large,  plump,  clean,  dry, 
and  of  a  silver  white  colour  on  the  surface. 

The  true  original  grana  sylvestra  seem  to  have  been 
very  different  from  the  composition  which  is  at  present 
sold  under  that  denomination  in  this  kingdom,  and  which 
has  the  appearance  of  a  dry  powder,  with  many  small 
lumps  or  fragments  of  something  which  had  been  pre- 
viously formed  into  a  cake  or  dried  uniform  mass.  It 
affords,  though  in  an  inferior  degree,  some  of  the  same 
sort  of  colour  as  cochineal,  but  in  a  small  proportion; 
six  pounds  being  necessary,  according  to  my  experi- 
ments, to  dye  as  much  cloth  as  one  pound  of  the  fine 
cochineal;  whereas  the  true  grana  sylvestra  are  repre- 
sented as  yielding  at  least  half  as  much  as  the  fine,  and 
they  sell  for  at  least  half  the  price  in  some  parts  of  Eu- 
rope, whilst  here  the  substance  so  called,  and  which  has 
not  the  least  appearance  of  any  insect,  sells  at  present 
for  less  than  an  eighth  of  the  price  of  fine  cochineal. 
Probably  it  is  composed  of  the  white  downy  substance 
which  the  wild  insects  are  represented  as  leaving  in 
great  abundance  on  the  nopals,  and  of  other  excremen- 
titious  matters  deposited  by  them,  joined  to  fragments, 
broken  limbs,  and  dust,  of  the  insects  themselves,  and 
perhaps  with  an  addition  of  some  vegetable  matters,  all 
beat  up  into  one  uniform  mass.  Something  of  this  sort 


Philosophy  of  Permanent  Colours.  323 

was  formerly  practised  even  with  the  true  cochineal, 
according  to  Dr.  Brown,  who  says,  **  The  cochineal 
insects  used  to  be  prepared  by  pounding  them,  and 
steeping  the  pulp  in  the  decoction  of  the  texuatla,  (a 
species  of  melastoma,  as  he  supposes,)  or  that  of  some 
other  plants,  which  they  observed  to  heighten  the  co- 
lour. This  (continues  Dr.  Brown)  was  left  to  settle  at 
leisure,  and  afterwards  made  into  cakes  and  dried  for 
the  market."  Hernandez  also  mentions  that  in  his  time 
cakes  were  made  from  cochineal  in  Mexico.  Probably 
the  true  grana  sylvestra,  mixed  with  fragments  of  the 
true  cochineal,  compose  what  is  sold  in  this  country 
under  the  name  of  granillo,  which  appears,  as  the  name 
indeed  imports,  to  consist  chiefly  of  insects  somewhat 
smaller  than  those  composing  the  fine  cochineal,  and 
therefore,  in  that  respect,  answers  to  the  best  authenti- 
cated descriptions  of  the  wild  cochineal. 

It  had  been  generally  believed  that  the  cochineal  de- 
rived its  colour  from  the  red  or  crimson  fruit  of  the 
nopals,  and  other  species  of  opuntias;  and  I  was  for- 
merly  induced  by  this  opinion  to  make  various  trials 
with  the  red  fruit  of  the  cactus  opuntia  for  dyeing,  in- 
stead of  cochineal.  They  all,  indeed,  proved  unsuccess- 
ful; but  I  was  disposed  to  attribute  my  failure  to  the 
want  of  that  kind  of  animalization,  which  the  vegetable 
red  colouring  matter  was  supposed  to  receive,  when 
eaten  and  assimilated  by  the  insect:  and  I  thought  it 
probable,  that  other  vegetable  colouring  matters  might 
be  equally  improved  in  the  same  way,  and  that  perhaps, 
instead  of  insects,  it  might  be  advantageous  to  employ 
larger  animals  for  this  purpose.*  It  is,  how^ever,  now 

*  Dr.  Garden  relates,  that  a  negro  woman  in  South  Carolina, 
who  then  gave  suck,  having  eaten  six  of  the  red  fruit  of  the  prickly- 
pear,  (cactus  opuntia),  and  some  of  her  milk  being  collected,  and 
left  until  the  cream  had  separated,  this  last  was  found  to  be  of  a 


324  Phildsophy  of  Permanent  Colours. 

certain,  from  the  observations  of  M.  Thiery  de  Me- 
nonville,  and  from  other  well-attested  relations,  that  the 
cochineal  insects  do  not  feed  on  the  red  fruit  of  the  cac- 
tus, but  upon  its  branches  or  articulations,  to  which 
they  adhere,  and  which  contain  nothing  like  a  red  juice; 
and  that  they  sometimes  live,  propagate,  and  preserve 
their  colour  on  those  species  of  cactus  which  do  not  bear 
red-coloured  fruits:  consequently,  the  colour  of  these  in- 
sects does  not  result  from  that  of  their  food,  but  from 
their  peculiar  constitution  and  organization.* 

reddish  colour,  considerably  weaker,  iiKleed,  than  the  lively  red 
which  the  urine  was  found  to  acquire  by  the  same  fruit.  See  Phi- 
losoph.  Trans,  vol.  50,  p.  269.  In  the  third  volume  of  the  same 
Transactions,  mention  is  made  of  a  berry  growing  in  Bermudas, 
and  called  the  "  Summer  Island  Redweed,  which  berry  is  as  red  as 
the  prickly  pear,  and  giving  much  the  like  tincture;  out  of  which 
berry  cometh  out  first  worms,  which  afterwards  turn  into  flies, 
(somewhat  bigger  than  the  cochineal  fly,)  feeding  on  the  same 
berry,  in  which  there  hath  been  found  a  colour  no  whit  inferior  to 
the  cochineal  fly." 

*  Although  the  facts  here  stated  were  published  more  than  eigh- 
teen years  ago,  the  error  which  they  were  intended  to  correct,  not 
only  subsists,  but  continues  to  be  propagated  by  weighty  authorities. 
M.  Fabroni,  who  was  lately  mentioned  at  p.  214,  asserts,  (Ann.  de 
Chimie,  torn.  xxv.  p.  301)  that  the  cochineal  insect  can  with  its 
proboscis  extract  from  the  nopal  its  juice,  which  afterwards  com- 
municates its  fine  red  colour  to  the  insect;  and  this  juice,  he  adds, 
"  selon  moi,  est  le  meme  que  la  nature  nous  presente  a  nu  dans  les 
fruits  murs  de  cette  meme  plante." 

Bouillon  La  Grange  also  endeavours  to  maintain  the  same  error, 
in  his  Manuel  de  Chimie,  tom.  ii.  p.  743,  where  he  asserts  that  the 
cactus  coccinillifer  "  communique  son  sue  rouge  a  Tinsecte,  qui 
s'en  neurit"  But  a  more  important  support  has  been  given  to  this 
error  by  the  author  of  a  respectable  botanical  work,  now  publishing 
in  Jamaica,  under  the  title  of  Hortus  Jamaicensis,  in  two  volumes 
4to.;  who  not  only  adopts  the  error,  but,  to  confirm  it,  has  (vol.  i. 
p.  412)  adduced  copious  extracts  from  Mr.  Long's  History  of  Ja- 
maica, (a  work  in  great  estimation,)  of  which  extracts  the  following 
aire  a  part,  viz,  «  This  juice  (of  the  fruit  of  the  cactus)  is  the  natu- 


Philosophy  of  Permanent  Colours.  325 

The  very  great  demand  for  cochineal,  almost  imme- 
diately after  it  had  been  made  known  in  Europe,  caused 
a  very  rapid  multiplication  thereof  in  the  Spanish  Anie- 

ral  food  of  the  cochineal  insect,  which  owes  to  it  the  value  and 
property  it  possesses  as  a  dye  in  some  of  our  principal  manufac- 
tures. The  exuvia  and  animal  salts  of  the  insect  are,  from  the  mi- 
nuteness of  its  parts,  insepara!  le  from  the  essential  principles  of 
the  dye;  whence  it  follows,  that  such  a  heterogeneous  mixture 
must  necessarily  destroy  the  brilliancy  of  colour  inherent  to  the 
juice  of  this  fruit;  and  that  the  juice  itself,  which  alone  contains 
the  dyeing  principle,  must,  if  unmixed  and  brouj^ht  to  consistence, 
yield  a  true  perfect  colour,  lively  and  brilliant,  as  we  find  it  in  its 
natural  state." 

"  Upon  this  hypothesis,  Mr.  David  Riz,  an  ingenious  gentleman 
of  Kingston,  in  this  island,  proceeded  in  several  experiments  to 
obtain  from  the  plant  artificially,  what  nature  accomplished  in  the 
insect,  and  at  length  happily  succeeded,  by  inspissating  the  juice; 
but  the  means  he  used  are  not  yet  communicated  to  the  public. 
Encouraged  by  this  discovery,  he  went  to  England  with  seventy- 
six  processes,  diiferently  manufactured,  to  try  which  would  an- 
swer best  as  a  substitute  to  the  cochineal.  After  a  great  number  of 
experiments,  he  found  one  process  which  communicated  a  crim- 
son colour  to  silk  and  wool,  superior  to  that  given  by  cochineal; 
trials  of  which  were  made  before  a  number  of  the  principal  dyers 
in  and  about  London,  at  the  Museum  of  the  Royal  Society^  invited 
there  for  that  purpose.  He  also  found  two  other  processes,  which 
promised,  with  very  little  alteration  in  their  manufactory,  to  afford 
the  colour-making  dyes  of  scarlet  and  purple.  Upon  a  moderate 
calculation  it  was  found,  that  his  colour  would  go  further  than 
three  times  the  quantity  of  cochineal,  which  he  accounted  for  by 
remarking  that  there  is  a  great  part  of  the  insect,  as  its  skin,  &c. 
which  affords  no  dye,  but  that  the  whole  of  his  process  was  ge- 
nuine colour,  with  little  or  no  impurity." 

**  Notwithstanding  the  advantages  that  might  be  derived  to  the 
nation  from  this  gentleman's  discovery,  he  met  upon  the  whole 
with  very  little  encouragement  to  prosecute  bis  manufacture  fur* 
ther."  Long's  History,  &c.  p.  731. 

Upon  this  statement  I  shall  only  observe,  that  if,  in  fact,  Mr. 
Riz  did,  as  is  alleged,  produce  any  substance  or  preparation  capable 
of  dyeing  a  good  scarlet,  and  of  producing  as  much  colour  as  three 
Hmes  its  weight  of  cochineal,  he  must  have  obtained  it  otherwise 


326  Philosophy  of  Permanent  Colours* 

rican  settlements.  It  appears  from  Acosta's  statement, 
that  so  early  as  the  year  1587,  there  came  to  Spain,  by 
a  single  flota,  no  less  than  5670  arobas  of  fine  cochineal, 
which,  at  the  rate  of  251bs.  each,  weighed  14i,7501bs.; 
and  the  common  annual  importation,  as  stated  some 
years  since  by  the  Abbe  Raynal,  has  amounted  to  4000 
quintals,  or  400,000lbs.  weight  of  the  fine  cochineal, 
300  quintals  of  the  grana  sylvestra,  200  ditto  of  granillo, 
and  100  of  cochineal  dust,  which  were  computed  to 
have  sold  for  a  sum  equivalent  to  about  nine  millions 
of  French  livres;  without  reckoning  considerable  quan- 
tities sent  directly  from  America  to  the  Philippine 
islands,  for  supplying  a  considerable  part  of  Asia.  The 
European  importations  have,  however,  been  considera- 
bly increased,  during  several  of  the  last  years.*  Since, 

than  fmm  the  cactus,  and  probably  it  must  have  been  an  extract  of 
cochineal,  like  those  preparations  commonly  sold  under  the  name 
of  carmine,  except  that  it  may  have  contained  none  of  the  alumi- 
nous basis,  or  that  of  tin.  For  what  purpose  such  an  imposition  was 
practised,  I  am  not  bound  to  inquire.  But  certainly  the  red  fruit  of 
any  and  every  species  of  cactus,  is  as  incapable,  as  a  cranberry,  of 
affording  a  colouring  matter  similar  to  that  of  cochineal;  and  since 
it  has  become  notorious  that  this  insect  does  not  meddle  with  the 
fruit,  (the  only  part  of  the  cactus  which  exhibits  a  red  colour)  the 
notion  which  I  now  combat,  has  been  left  without  any  foundation 
or  probability.  I  have  already  stated  that  the  colouring  matter  of 
the  kermes,  is  similar  to  that  of  cochineal,  and  yet  nobody  has  ever 
suspected  the  kermes  to  derive  its  colour  from  the  leaves  of  the 
oak,  on  which  it  is  produced,  there  being  no  red  juice  in  these 
leaves,  nor  indeed,  in  those  parts  of  the  cactus  to  which  the  cochi- 
neal insects  attach  themselves  exclusively.  An  error  similar  to 
the  preceding,  seems  to  have  subsisted  formerly  in  regard  to  the 
f.ur file -giving  murex,  as  mentioned  by  Aristotle  (Hist.  Animal,  vi. 
cap.  Ed.  Scaliger,)  who  says  that  a  sea-weed  (Fucus)  probably  Or- 
chella,  having  been  cast  on  shore  near  the  Hellespont,  which  yield- 
ed a  purple  colour,  the  neighbouring  inhabitants  concluded  it  to  be 
the  food  of  the  purple  shell-fish. 
*  This  was  written  in  1793. 


Philosophy  of  Permanent  Colours,  327 

according  to  very  good  information,  which  I  have  re- 
ceived, the  quantities  of  fine  cochineal  brought  to  Spaia 
in  the  years  1788,  1789,  and  1790,  amounted  to  eleven 
thousand  bags,  weighing  200lbs.  each,  and  making  to- 
gether 2,200,000lbs.  weight;  and  between  the  first  of 
January  1791,  and  the  first  of  October  in  the  same  year, 
the  importations  had  exceeded  2000  bags. 

It  must,  however,  be  observed,  that  the  importations 
during  these  years  were  somewhat  greater  than  usual, 
because  an  advance  in  the  price  of  cochineal  in  Europe 
had  induced  the  holders  of  it  in  America  to  send  their 
stocks  more  speedily  to  market,  in  order  to  avail  them- 
selves of  the  higher  prices;  and,  from  accurate  calcula- 
tions, I  think  it  may  be  concluded,  that  the  average 
quantity  of  fine  cochineal  annually  consumed  in  Europe 
amounts  to  about  three  thousand  bags,  or  600,0001bs. 
weight,  of  which  about  1200  bags,  or  240,0001bs.  weight, 
may  be  considered  as  the  present  annual  consumption 
of  Great  Britain.  A  greater  quantity  comes  indeed  into 
the  kingdom,  but  the  surplus  is  again  exported  to 
other  countries.  These  1200  bags  may  be  supposed  to 
cost  180,000/.  sterling,  valued  at  \5s.  per  lb.  which  has 
been  about  the  average  price  for  some  years  past.*  Ac- 
cording to  Don  Antonio  Ulloa,  the  greatest  quantities 
of  cochineal  are  produced  at  Oaxaca,  Tlascala,  Chulula, 
Neuva  Gallicia,  and  Chiapa,  in  New  Spain,  and  at  Ham- 
batio,  Loja,  and  Tucuman,  in  Peru. 

About  six  years  ago,  Dr.  James  Anderson,  physician- 
general  on  the  company's  establishment  at  Madras,  per- 
suaded himself  that  he  had  found  the  true  cochineal  in- 

*  Since  the  year  1793,  the  price  of  cochineal  has  more  than 
doubled;  it  has  continued  during  the  last  eight  years  at  more  than 
30s.  the  pound,  and  has  sometimes  exceeded  50s.  But  this  augmen- 
tation of  price,  or  a  change  of  fashion,  seems  to  have  considerably 
diminished  the  annual  consumption  of  Great  Britain,  which  may 
now  be  estimated  at  about  750  bags. 


328  Philosophy  of  Permanent  Colours. 

sects  subsisting  .naturally  on  a  species  of  salt  grass  iu 
that  part  of  India;  and  some  parcels  of  a  dried  insect, 
probably  of  the  coccus  kind,  (but  more  like  the  kermes,) 
which  he  mistook  for  the  true  coccus  cacti,  were  sent 
by  him  to  this  country;  of  which  I  made  several  trials, 
at  the  request  of  a  friend,  (as  others  also  did,)  and  found 
them  to  be  neither  of  the  same  species,  nor  possessed 
in  any  degree  of  that  particular  colouring  matter  for 
which  the  cochineal  insect  is  so  highly  valued;  though 
in  their  dried  state  they  had  nearly  the  same  external 
appearance,  excepting  their  size,  which  was  considera- 
bly less  than  that  of  the  true  Mexican  cochineal;  but 
upon  rubbing  them  in  a  mortar,  I  soon  perceived,  that 
instead  of  breaking  into  a  dry  powder  like  cochineal, 
they  could  only  be  beat  into  a  kind  of  unctuous  paste; 
nor  would  any  degree  of  drying,  short  of  combustion, 
overcome  this  unctuous  quality,  or  render  them  capable 
of  being  rubbed  into  the  form  of  a  powder;  and  in  point 
of  colour  there  was  a  more  essential  difference,  since 
they  produced  nothing  better  than  a  chocolate  brown, 
by  the  means  usually  employed  for  dyeing  scarlet  with 
cochineal,  nor  indeed  by  any  other  means.  This  choco- 
late colour  proved  indeed  sufficiently  durable  on  wool; 
but  it  may  be  dyed  so  cheaply  by  other  matters,  and 
indeed  these  insects  yielded  so  little  of  it,  that  they 
never  can  be  worth  collecting  as  a  dyeing  drug.* 

It  occurred  to  me,  however,  on  this  occasion,  that 
though  Dr.  Anderson  had  failed  in  his  expectation  of 

*  The  Company,  in  their  letter  of  the  31st  of  July,  1787,  to  the 
government  of  Madras,  were  pleased,  from  very  laudable  motives, 
to  direct,  that  every  further  pursuit  respecting  this  species  of  in- 
sects, "  should  be  effectually  discouraged,"  because,  "  were  it  to 
fall  into  the  hands  of  improper  persons,  it  might  be  made  use  of 
to  mix  with  and  adulterate  the  real  cochineal,  to  the  great  injury 
of  the  consumer,  as  it  would  most  assuredly  spoil  the  beauty  of 
every  scarlet  done  therewith." 


Philosophy  of  Permanent  Colours,  32^ 

finding  the  cochineal  in  a  country  where  it  probably 
never  existed,  (the  genus  of  plants  on  which  it  is  natu- 
rally fitted  and  destined  to  live  having  been  originally 
produced  only  in  America,)  yet  it  would  not  be  very 
difficult  to  convey  both  the  insects,  and  the  cactus  co- 
chenillifer  (their  natural  food  and  habitation)  to  the 
East  Indies,  and  there  propagate  both,  so  as  in  a  few 
years  to  obtain  from  thence  ample  supplies  of  a  drug  so 
highly  important  in  a  great  manufacturing  country,  and 
for  which  nearly  200,000/.  sterling  are  annually  paid  by 
this  to  the  Spanish  nation,  especially  as  great  advan- 
tages in  this  respect  would  result  from  the  cheapness  of 
labour  and  subsistence  in  the  East  Indies;  and  consider- 
ing moreover  how  much  the  quality  of  the  indigo  of 
that  country  had  been  improved,  and  the  quantity  in- 
creased  within  a  few  years,  through  the  measures  taken 
so  opportunely  for  these  purposes  by  the  East- India 
Company,  at  a  time  when  the  usual  supplies  of  that  ar- 
ticle from  other  countries  had  been  greatly  diminished. 
Similar  ideas  on  this  subject  occurred,  or  were  sug- 
gested, to  the  Directors  of  the  East- India  Company, 
who,  in  the  spring  of  the  year  1788,  procured  from  his 
Majesty's  botanic  garden  at  Kew  (through  Sir  J.  Banks, 
Bart.  P.  R.  S.),  some  of  the  true  nopal  plants ,  two  of 
which  were  sent  out  by  the  Bridgwater,  during  that 
season,  to  Madras,  and  put  under  the  care  of  Dr.  An- 
derson, where  they  have  since  been  multiplied  to  seve- 
ral thousands,*  and  been  transplanted  from  thence  to 
Bengal,  and  St.  Helena,  in  order  that  a  sufficient  stock 
might  be  in  readiness  to  receive  any  cochineal  insects 
which  should  arrive;  a  committee  of  the  Directors  hav- 

*  It  has  since  been  ascertained  that  these  plants  were  not  the  true 
nofid^  or  cactus  coccinillifer,  but  a  different  species,  much  less  suit- 
ed to  the  purpose  for  which  they  were  intended. 

Vol.  L  2  T 


330  Philosophy  of  Permanent  Colours. 

ing  previously  reported  as  "their  opinion,  that  it  be  re- 
commended to  the  Committee  of  Correspondence  to 
take  such  measures  as  they  shall  judge  best  suited  for 
procuring  from  America  a  quantity  of  the  cochineal  in- 
sect, with  a  view  to  the  introduction  of  the  same  upon 
the  coast  of  Coromandel."  Unfortunately,  however,  it 
does  not  appear  that  any  measures  have  yet  been  effec- 
tual in  procuring  the  domesticated  insect,  or  even  the 
sylvestra,  though  this  last  exists  in  Jamaica,  (as  does 
the  true  nopal*)  and  in  many  other  accessible  parts  of 
America,  and  probably  in  more  than  ordinary  perfection 
in  Brasil;  at  least  I  made  trial  about  the  year  1787  of 
some  which  had  been  sent  from  thence  by  the  way  of 
Lisbon,  and  which  yielded  full  as  much  colour,  and  of 
as  much  beauty,  as  half  its  weight  of  the  very  best  fine 
cochineal;  and  until  this  last  can  be  obtained,  would  it 
not  be  advisable  to  make  trial  of  the  other,  which,  by- 
being  properly  nursed,  and  nourished  upon  the  true 
nopals,  might  perhaps,  in  a  little  time,  improve  so  as  to 
supersede  the  necessity  of  seeking  any  farther?! 

*  The  cactus  coccinillifer,  and  the  cactus  Pereskia  (or  Spanish 
gooseberry),  are  both  mentioned  in  a  recent  catalogue  of  the  Hor* 
(us  Eastensisy  as  growing  in  the  botanical  garden  of  the  late  Mr. 
East,  at  Jamaica;  und  others  are  said  to  be  growing  in  Longvillc 
Garden,  in  the  same  island. 

t  Subsequently  to  this  suggestion,  and  as  I  believe  in  conse- 
quence of  it,  some  of  the  Brasilian  cochineal  insects  were  carried 
to  India  by  one  of  the  Compaiiy's  ships  which  had  touched  at  that 
part  of  America,  and  some  quantities  of  cochineal  have  been  at  dif- 
ferent times  imported  to  this  country,  which  were  derived  from  the 
Brasilian  stuck.  1  had  collected  authentic  and  valuable  information 
on  this  subject,  and  had  made  experiments  with  the  cochineal  itself; 
but  the  papers  containing  an  account  of  them,  and  of  the  informa- 
tion so  collected,  have  been  unaccountably  lost  or  purloined,  with 
others,  probably  of  more  importance,  and  I  dare  not  rely  on  my 
recollections  so  far  as  to  enter  upon  any  statement  of  their  con- 
tents. 


Philosophy  of  Permanent  Colours.  ,  331 


CHAPTER  IV, 

Of  the  Properties  and  Uses  of  Cochineal;  with  an  account 
of  new  Observations  and  Experiments  calculated  to 
improve  the  Scarlet  Dye. 

"  Le  travail  a  6t6  mien,  le  profit  en  soit  au  lecteur." 

Jean  Ret. 

In  the  English  translation  of  Clavigero's  History  of 
Mexico,  the  ancient  inhabitants  of  that  country  are  said  to 
have  obtained  a  purple  colour  from  cochineal.  Probably, 
however,  either  the  author  or  translator  of  that  work,  has 
mistaken  purple  for  crimson;  this  last  being  the  natural 
colour  of  cochineal,  and  what  it  always  affords  with  the 
aluminous  basis,  which  Clavigero,  in  another  part  of  his 
history,  says  the  Mexicans  had  been  used  to  employ  in 
early  times;  though  it  certainly  is  difficult  to  understand 
how  they  could  have  become  acquainted  with  it.  This 
account  moreover  accords  with  that  of  Herrara,  who,  after 
mentioning  the  Tuna  or  Nopal  of  Tlaxcalla,  says,  '*  Op- 
timum longe  granum  dat  Tlaxcallum  cujus  indigenas 
prestantissimam  tincturam  ex  illo  conficiunt,  hoc  modo, 
comminuunt  et  macerant  in  decocto  aluminis,  et  ubi  re- 
sederit,  cogunt  in  tabellas,  quas  Hispani  vocant  grana  en 
pan.''^ 

There  is  also  reason  to  conclude,  that  during  a  number 
of  years,  none  but  the  aluminous  basis  was  used  for  dye- 
ing with  cochineal  in  Europe,t  until  the  accidental  falling 
of  a  solution  of  tin  by  aqua-fortis,  into  a  decoction  of  co- 

*  Whilst  alum  was  the  only  mordant  employed  with  cochineal, 
these  grain  cakes  made  with  a  decoction  of  alum  might  answer  very 
well,  but  not  afterwards. 

t  Caneparius  (de  Atramentis,  p.  191),  mentions  the  dye  "ex 
granis  ficus  Indicae  Mexicani,  quae  prout  semina  sunt,  eisque  tinc- 
tprcs^pro  carbmno  colore  utuntur."  Hence  it  appeal's  that  cochinea! 


332  Philosophy  of  Permanent  Colours, 

chineal,  about  the  year  1630,  manifested  the  singular  pow- 
er of  the  oxide  of  that  metal  in  exalting  the  colour  of  this 
drug,  and  led  to  a  discovery  of  th^uinost  vimd  of  all  co- 
lours, the  cochineal  scarlet,  Kunckel  and  others  state  this 
accident  to  have  happened  to  a  German,  named  Kuster 
or  Kuffier,  But  others,  and  particularly  Beckman,  assert 
thcit  it  occurred  to  a  Dutch  chemist,  Cornelius  Drebbel, 
who  was  born  at  Alkmaar,  and  died  at  London  in  1634,* 
and  that  he  communicated  this  occurrence  to  Kulfler, 
who  was  an  excellent  dyer  at  Ley  den,  and  afterwards  be- 
came the  son-in-law  of  DrebbeLf  That  Kuffler  put  the 
discovery  into  practice  in  his  dye-house,  and  that  the  scar- 
let was  thence  first  named  Kuffler's  colour,  and  after- 

was  then  (1619)  only  used  for  dyeing  crimson,  at  Venice,  where 
the  art  of  dyeing  had  long  been  naost  successfully  practised. 

*  If  it  be  true  that  Drebbel  died  in  London  in  1634,  he  had  pro- 
bably come  to  England  to  derive  some  benefit  from  his  discovery, 
and  died  before  he  had  time  to  do  so. 

t  Mr.  Macquer,  in  a  memoir  printed  among  those  of  the  Aca- 
demy of  Sciences  at  Paris  for  1768,  says,  "  Drebbel,  chimiste  Hol- 
landois,  a  imagine  d'employer  dans  la  teinture  de  cochenille,  de  la 
dissolution  d*etain  faite  par  Teau  r6gale,  et  dcs  lors  on  a  obtenu  le 
plus  vif  et  le  plus  eclatant  de  tons  les  rouges  dontTartjCt  meme  la 
nature^nous  ait  donne  Tidee;  je  veux  dire  r6carlate  couleur  de  feu, 
qui  a  porte  d*abord  le  nom  c^cscarlate  de  Hollander  parce  que  c'est 
dans  ce  pays  que  les  premieres  manufactures  ont  ete  etablies,"  &c. 

Mr.  Macquer  seems  to  have  been  mistaken  in  supposing  that  the 
first  solutions  of  tin  employed  in  this  way  were  nitro-muriatic,  or 
made  with  aqua-regia,  there  being  very  good  reason  to  believe,  that 
aqua-fortis  alone,  though  perhaps  impure,  was  used  for  some  years 
for  this  purpose. 

Mr.  Delaval,  without  the  smallest  probability,  attempts  to  carry 
the  first  use  of  tin  for  dyeing  back  to  very  remote  antiquity;  and 
thinks  the  Phoenicians  used  that  which  they  were  said  to  have 
brought  from  Britain  in  this  way,  because  (as  he  erroneously  as- 
serts) "  this  is  necessary  to  the  production  of  red  colours,  whether 
from  animal  or  vegetable  materials."  See  Experimental  Enquiry, 
&c. 


Philosophic  of  Permanent  Colours*  333 

wards  scarkt  of  Holland,  or  Dutch.  From  him  a  Flemish 
paintei,  Kloeck  or  Giuck,  karned  the  secret,  and  com- 
municated it  to  one  of  the  famous  Gobelins  at  Paris;  and 
another  Fleming,  named  Kepler,  brought  the  secret  to 
England  about  the  year  1643,  and  the  first  dye-house  for 
dyeing  the  new  scarlet  having  been  soon  after  establish- 
ed at  Bow^  near  London,  that  colour  was  for  some  years 
called  the  Bow  dye. 

It  has  been  generally  supposed,  that  after  the  effects  of 
tin  upon  the  cochineal  colour  had  been  discovered,  as  be- 
fore  mentioned,  nothing  more  was  wanting  to  produce 
what  is  at  present  called  scarlet,  than  to  apply  the  colour 
so  produced  as  a  dye  to  wool;  or  in  other  words,  that  a 
nitric,  or  nitro-muriatic  solution  of  tin,  was  sufficient  to 
change  the  natural  crimson  of  cochineal  to  a  scarlet.  Such 
at  least  has  been  the  opinion  of  every  writer  on  the  sub- 
ject until  the  present  hour;  though  it  will  hereafter  be 
proved  to  have  been  an  erroneous  opinion,  and  that  the 
nitric  solution  of  tin  invariably  produces  (with  cochineal) 
a  crimson  or  rose  colour,  and  not  a  scarlet,  unless  other 
means  be  also  employed  to  incline  die  cochineal  colour, 
so  far  as  may  be  necessary,  towards  the  yellow;  and  the 
means  of  doing  this  seem  to  have  been  stumbled  upon, 
and  continually  employed  without  any  knowledge  of  their 
true  eifect.  I  have  already  mentioned  that  tartar  is,  and 
for  many  ages  appears  to  have  been,  generally  employed 
with  alum,  to  compose  the  ordinary  boiling  liquor  or 
mordant  for  woollen  cloths:  and  it  seems  probable,  that 
when  the  first  attempts  were  made  to  employ  the  solution 
of  tin,  instead  of  alum,  it  would  naturally  have  been  ima- 
gined, that  as  tartar  had  been  found  useful  with  the  latter, 
it  must  also  produce  good  effects  with  the  former,  and 
that  a  trial  of  it  having  been  thus  produced,  and  the  most 
brilliant  of  all  colours  having  been  found  to  result  from 
this  combination  of  tartar  with  the  solution  of  tin,  their 


334  Philosophy  of  Permanent  Colours. 

joint  use  was  afterwards  continued,  without  any  inquiry- 
concerning  the  particular  share  which  either  of  them  had 
in  producing  such  pleasing  effects. 

At  first  indeed  a  diluted  nitric  acid  appears  to  have 
been  employed  for  dissolving  the  tin  without  any  admix- 
ture of  the  muriatic;*  but  as  the  former  would  have  held 
but  a  small  portion  of  the  calx  of  that  metal  in  a  state  of 
suspension,  and  as  even  that  portion  would  have  been 
liable  to  precipitate  in  a  few  days,  the  practice  of  adding 
either  a  little  muriate  of  ammonia,  or  a  little  sea-salt,  to 
the  aqua-fortis,  and  of  thereby  producing  an  aqua-regia, 
or  nitro-muriatic  acid,  seems  to  have  been  introduced, 
though  it  did  not  become  general  until  a  considerable 
time  after;  since  Hellot  gives  an  account  of  the  process 
used  in  his  time  for  dyeing  scarlet  at  Carcassonne,  in  which 
tin  was  dissolved  only  by  diluted  aqua-fortis;  and  he  men- 
tions M.  Baron,  as  claiming  the  merit  of  having  been  the 
first  in  that  city  who  employed  an  aqua-regia  for  dissolv- 
ing tin,  in  order  to  prevent  a  precipitation  of  its  calx  or 
oxide;  and  even  when  this  was  done,  the  muriate  of  am- 
monia and  sea- salt  were  added,  but  very  sparingly,  from 
a  belief,  which  still  subsists  universally,  that  a  more  libe- 
ral use  of  either  of  them  in  this  way,  or  of  the  muriatic 
acid  in  their  stead,  would  render  the  cochineal  colour  a 
crimson  instead  of  the  scarlet,  which  last  is  supposed  to  be 
a  peculiar  production  of  the  nitrate  of  tin,t  though  nothing 
can  be  more  groundless  than  this  belief;  since  the  nitrate, 
and  the  muriate  of  tin,  both  equally  afford  a  crimson 

*  Doubtless  the  aqua-fortis  was  then  impure,  by  containing  at 
least  a  small  proportion  of  the  muriatic  acid,  as  it  commonly  does 
at  this  time. 

t  I  give  this  denomination  to  solutions  of  tin  produced  solely  by 
a  diluted  nitric  acid,  without  regarding  the  decomposition,  more  or 
less  complete,  which  the  acid  undergoes  in  consequence  of  such 
solution . 


Philosophy  of  Permanent  Colours,  335 

colour  with  cochineal,  and  neither  aflfords  a  scarlet  with- 
out the  aid  of  other  means. 

The  dyer's  ordinary  solution  of  tin  is  made  with  that 
species  of  diluted  nitric  acid,  called  single  aqua-fortis, 
and  which,  as  usually  prepared,  is  capable  of  dissolving 
about  one-eighth  of  its  weight  of  tin,  grained  or  granu- 
lated, by  pouring  it,  when  melted,  into  water,  briskly 
agitated  with  a  bundle  of  rods,  or  by  other  suitable  means. 

For  each  pound  of  aqua-fortis,  it  is  usual  to  add  after 
the  rate  of  one  or  at  most  two  ounces  of  sea-salt,  though 
some  prefer,  and  probably  with  reason,  the  muriate  of 
ammonia  for  this  purpose.  About  half  as  much  water  as 
of  aqua-fortis,  is  moreover  commonly  added,  in  order 
still  farther  to  dilute  the  acid,  and  moderate  its  action  on 
the  tin.  Those  solutions  of  it  which  are  made  most  slow- 
ly, and  with  the  least  separation  of  fumes  or  vapours,  have 
been  found  to  succeed  the  best;  probably,  because  in 
these  the  tin  is  less  calcined,  or  oxygenated,  and  the  solu- 
tion retains  a  larger  portion  of  azote,  or  nitrogene,  than 
in  those  which  proceed  more  rapidly.  It  is  usual  to  allot 
after  the  rate  of  two  ounces  of  grained  tin  to  every  pound 
of  aqua-fortis;  and  the  metal  is  put  into  it,  at  different 
times,  waiting  until  one  part  is  nearly  dissolved,  before 
another  is  added,  lest  too  much  heat  should  be  evolved, 
and  the  solution  proceed  too  rapidly;  though  there  is  no 
danger  of  this,  in  the  latter  part  of  the  process,  which  in- 
deed should  be  protracted  so  as  to  last  two  or  three  da}^. 
The  water  mixed  with  the  aqua-fortis  should  be  ascer- 
tained by  weighing  or  measuring,  in  order  that  a  proper  al- 
lowance may  be  made  for  it  in  calculating  the  strength  of 
the  solution,  or  the  weight  of  metal  contained  in  a  given 
quantity  thereof,  which,  supposing  half  as  much  water  as 
of  aqua-fortis  to  have  been  used,  will  be  about  one-four- 
teenth part  of  the  whole;  and  when  the  solution  (which  the 
dyers  in  this  country  generally  call  spirit)  has  been  made 


336  Philosophy  of  Permanent  Colours. 

in  these  proportions,  from  eighteen  to  twenty  five  pounds 
of  it  are  commonly  employed  to  dye  a  full  cochineal  scar- 
let,  upon  one  hundred  pounds  weight  of  woollen  cloth; 
and  of  this  quantity  three-fifths,  or  two-thirds,  are  usually 
employed  in  the  first  preparation,  or  boiling  part  of  the 
process;  for  which  supposing  one  hundred  pounds  weight 
of  cloth  are  intended  to  be  dyed,  about  eight  pounds  of 
crude  tartar  or  argol  are  put  into  a  suitable  dyeing  kettle 
or  vessel,  (of  pure  block  tin,)  with  a  sufficient  quantity  of 
clean  soft  water,*  and  six  or  eight  ounces  of  powdered 
cochineal.  Immediately  after  this  twelve  or  fourteen 
pounds  of  the  solution  of  tin,  prepared  as  before  men- 
tioned, are  to  be  added,  and  when  the  mixture  is  nearly 
ready  to  boil,  the  cloth,  being  first  thoroughly  moisten- 
ed, (that  the  dye  may  penetrate  and  apply  itself  equally 
thereto,)  is  put  into  the  dyeing  liquor,  and  turned  through 
it  (by  the  winch)  very  quickly  at  first,  and  afterwards 
more  slowly,  whilst  the  liquor  continues  to  boil,  for  the 
space  of  an  hour  and  a  half  or  more,  after  which  it  is 
to  be  taken  out,  and  rinced  in  clean  water.  By  the  first 
boiling  or  preparation,  the  cloth  will  have  acquired  a 
flesh  colour.  For  the  second^  or  dyeing  process,  a  tin 
vessel  is  filled  with  clean  water,  and  when  this  appears 
almost  ready  to  boil,  five,  or  if  a  full  colour  be  wanted, 
five  and  one  half  pounds  of  cochineal  in  powder  are  to  be 
put  into  it,  and  well  mixed,  by  stirring  for  a  few  minutes; 
after  which,  the  remaining  part  of  the  solution  of  tin  is  to 
be  added,  and  the  whole  being  well  stirred,  the  cloth  is 
to  be  put  into  the  liquor,  and  turned  very  briskly 
through  it,  over  the  winch,  for  a  little  time,  in  order 
that  both  ends  may  receive  an  equal  portion  of  the  dye; 
after  which  it  may  be  turned  more  slowly  for  the  space 

*  Hard  water  tends  to  produce  a  rose  colour,  which  the  dyers 
commonly  endeavour  to  obviate,  by  boiling  bran  or  starch  in  their 
water. 


Philosophy  of  Permanent  Colours*  337 

of  half  an  hour,  or  until  the  dyemg  liquor  becomes  ex- 
hausted, when'  the  cloth  is  to  be  taken  out,  aired,  and 
rinced. 

An  ounce  of  fine  cochineal  is  generally  deemed  neces- 
sary for  dyeing  a  pound  of  cloth;  but  something  less 
than  this  portion  is  frequently  made  to  answer,  espe- 
cially for  coarser  cloths.^ 

It  is  not,  however,  necessary  to  follow'this  (which  is 
the  usual)  process  for  dyeing  scarlet.  I  have  often  given 
that  colour  very  well  at  one  single  though  protracted 
boiling,  by  mixing  the  whole  quantity  of  tartar,  and  so- 
lution of  tin,  and  adding  the  cochineal,  after  the  cloth  has 
boiled  ten  or  fifteen  minutes;  for  such,  in  this  case,  is  the 
attraction  of  wool  for  the  colouring  matter,  as  well  as  for 
the  oxide  of  tin,  that  it  will  take  up  both  very  freely,  and 
retain  them  permancntiy,  when  thus  mixed.  I  think, 
however,  that  in  this  way  the  cloth  may  be  liable  to  im- 
bibe both  the  mordant  and  the  colour,  with  some  ine- 
qualities, by  reason  of  the  differences  which  are  found  to 
subsist  not  only  in  the  wool  of  different  sheep,  but  even 
of  the  same  individual,  when  taken  from  diflerent  parts 
of  the  body,  as  was  noticed  at  p.  63;  and  that  it  will 
therefore,  always  be  safest  to  employ  a  previous  boiling, 
in  the  manner  commonly  practised,  to  overcome  the  ef- 
feet  of  these  inequalities,  by  forcing  a  sufficient  quan- 
tity of  the  mordant  or  basis,  into  the  pores  even  of  those 
sorts  of  wool  which  are  the  least  disposed  to  receive  it. 
This  boiling  may,  however,  be  shortened  to  a  single 

*  Hellot  directs  an  ounce  of  cochineal  for  each  pound  of  fine 
cloth.  Berthollet  prescribes  six  pounds  of  cochineal  for  every 
lOOlbs.  of  cloth.  Mr.  Hawker,  a  very  eminent  scarlet  dyer  in 
Gloucestershire,  assured  me,  that  for  fine  cloths  he  commonly 
.employed  four  pounds  of  cochineaij  for  every  60lbs.  of  cloth;  but 
that  for  coarse  cloths  he  seldom  exceeded  two  pounds  and  three 
quarters  for  that  quantity  of  cloth. 

Vol.  I.  2  U 


338  Philosophy  of  Fermanent  Colours. 

hour,  when  it  is  iDerformed  with  what  the  dyers  call  a 
seasoned  float ,  meaning  the  bath  or  preparation  liquor, 
which,  after  having  been  employed  for  the  same  pur- 
pose, is  replenished  according  to  the  ordinary  practice, 
with  a  fresh  portion  of  the  mordant,  &c.  and  thus  ren- 
dered more  efficacious  than  the  first. 

I  have  moreover  often  dyed  very  beautiful  scarlets,  by 
preparing  or  boiling  the  cloth  with  the  whole  quantity  of 
solution  of  tin  and  tartar  at  once,  (as  is  commonly  done 
with  alum  and  tartar,)  and  afterwards  dyeing  it  unrinced, 
with  the  whole  of  the  cochineal  in  clean  water  only;  and 
in  this  way  I  have  found  the  colouring  particles  so  com- 
pletely taken  up  by  the  cloth,  that  the  liquor  became  as 
clear  as  the  purest  water,  and  the  colour  was  generally 
very  perfect. 

Most  dyers,  besides  the  tartar  used  in  the  first  boil- 
ing, employ  half  as  much  of  it  as  of  cochineal  in  the 
second,  or  dyeing  part  of  the  process;  and  certainly  the 
doing  so  will  be  advantageous,  whenever  the  colour 
is  wanted  to  approach  nearer  than  ordinary  to  the 
orange  tint,  though  this  is  not  the  effect  which  would 
be  generally  expected  to  result  from  thence.  Poerner 
uses  no  cochineal  in  the  first  boiling,  nor  indeed  is  any 
necessary,  though  a  little  may  probably  help  to  decom- 
pose  the  oxide  of  tin,  and  fix  it  more  copiously  in  the 
fibres  of  the  cloth.  For  scarlet,  many  dyers  prefer  the 
red  argol  or  crude  red  tartar;  but  the  matter  to  which  it 
owes  this  colour  is  wholly  incapable  of  adding  any  colour 
to  that  which  the  wool  might  otherways  acquire,  and 
therefore  at  best  its  redness  will  prove  useless.  Wool  is 
seldom  dyed  scarlet,  until  it  has  been  spun,  wove,  and 
fulled;  because  the  yellowish  tendency  which  the  cochi- 
neal colour  acquires  from  tartar  in  the  dyeing  process,  is 
nearly  all  taken  away  in  the  fulling,  and  a  rose  produced 
instead  of  a  scarlet  colour. 


Philosophy  of  Permanent  Colours,  339 

M.  Berthollet  thinks  the  solution  of  tin,  before  descri- 
bed, does  not  affect  the  cochineal  colours,  merely  by  the 
proportion  of  that  metal  which  it  contains;  and  that  when 
either  sal-ammoniac,  saltpetre,  or  common  salt,  enter  the 
composition  of  an  aqua-regia,  the  compound  will  be  less 
acid  than  when  it  consists  of  the  nitric  and  muriatic  acids 
solely;  and  that  the  former  deserves  therefore  to  be  pre- 
ferred, as  having  a  less  violent  action  upon  the  fibres  of 
woollen  cloths,  and  upon  colouring  matters. 

It  is  remarkable,  that  during  the  present  century,  no 
considerable  improvement  has  been  made  in  the  process 
or  means  of  dyeing  scarlet;  a  circumstance  which  is  the 
more  extraordinary,  since  the  pre-eminent  lustre,  as 
well  as  the  costly  nature  of  this  dye,  have  rendered  it 
an  object  of  particular  attention,  not  only  to  dyers,  but  to 
eminent  chemists,  by  whose  researches  we  might  have 
expected,  that  at  least  every  obvious  improvement  there- 
in would  have  been  long  since  attained.  That  this,  how- 
ever, has  not  been  done,  will,  I  think,  manifestly  appear, 
by  the  following  statement  of  my  own  particular  obser- 
vations and  experiments  on  this  subject,  which  began  in 
the  year  1786.  Having  then  been  led  to  pour  boiling 
water  repeatedly  upon  powdered  cochineal  in  a  china 
bason,  and  to  decant  it  as  often  from  the  subsiding  inso- 
luble parts,  until  they  would  yield  no  more  colour,  I 
found  that  by  adding  a  little  potash,  or  soda,  to  this 
seemingly  exhausted  sediment,  and  pouring  fresh  boil- 
ing water  thereon,  a  farther  copious  extraction  of  colour 
instantly  displayed  itself,  equal,  as  far  as  I  could  judge, 
to  about  one- eighth  of  the  whole  of  that  which  had  been 
originally  contained  in  the  powdered  insects;  and  having 
by  repeated  trials,  constantly  found  this  effect,  I  too  hasti- 
ly concluded,  that  the  colour  thus  obtained  by  the  help 
of  potash,  was  so  far  of  a  resinous  nature,  or  so  intermix- 
ed with  a  resinous  matter,  as  to  have  always  been  inca- 


S40  Philosophy  of  Permanent  Colours. 

pable  of  being  extracted  by  the  means  usually  employed 
for  dyeing  with  cochineal;  and  that  if  it  should  be  found 
capable  of  yielding  colours  as  beautiful  and  permanent 
as  those  dyed  with  the  more  soluble  colouring  particles 
of  these  insects,  an  acquisition  might  be  made  of  so  much 
new  colouring  matter,  which  till  then  had,  as  I  conceived, 
been  always  thrown  away.  That  it  was  capable  of  yielding 
such  colours,  I  soon  ascertained,  by  repeatedly  extracting 
this  particular  colouring  matter  by  the  help  of  potash, 
and  afterwards  dyeing  small  pieces  of  cloth  with  it,  (in 
the  ways  usually  employed  for  dyeing  scarlet),  and  by 
comparing  and  exposing  them  to  the  weather,  with  other 
pieces  dyed  from  the  more  soluble  colouring  matter  of 
cochineal. 

Continuing  my  inquiries  on  this  subject,  I  soon  per- 
ceived that  the  colour,  denominated  scarlet,  must  in  fact 
be  a  compound  colour,  (like  green,  purple,  and  orange), 
consisting  probably  of  about  three-fourths  of  a  most 
lively  pure  crimson  or  rose  colour,  and  about  one-fourth 
of  a  pure  bright  yellow;  and  that  therefore,  when  the 
natural  crimson  of  the  cochineal  is  made  scarlet  by  the 
means  always  hitherto  employed  for  dyeing  that  colour, 
there  must  be  a  change  produced,  equivalent  to  a  con- 
version of  one- fourth  of  the  cochineal  colouring  matter 
from  its  natural  crimson  to  the  yellow  colour;  and  as  a 
better  yellow  might  be  obtained  from  other  drugs,  where 
it  naturally  exists,  and  for  a  fiftieth  part  of  what  it  costs 
when  obtained  in  this  way,  from  the  most  costly  of  all 
dyeing  drugs ^  (cochineal),  it  necessarily  followed,  that 
this,  the  universal  and  only  known  method  of  producing 
a  scarlet,  must  be  highly  injudicious,  because  unneces- 
sarily expensive. 

Convinced  of  this  important  truth,  and  at  the  same 
time  believing  too  easily,  on  the  authority  of  Hellot,  Mac- 
quer,  and  others,  that  the  natural  crimson  of  cochineal  was 


Philosophy  of  Permanent  Colours.  341 

rendered  scarlet  only  by  the  nitric  acid  employed  to  dis- 
solve the  tin  used  in  dyeing  that  colour,  I  began  a  series 
of  experiments  for  producing  it,  without  any  such  waste 
of  the  cochineal  colouring  matter.  For  this  purpose  it 
seemed  necessary  to  discover  a  mordant  or  basis,  capable 
of  permanently  fixing  and  strongly  reflecting  the  pure 
vivid  cochineal  crimson,  or  rose  colour,  without  making 
it  incline  to  the  yellow.  I  concluded,  and  found  by  ex- 
periments, that  the  necessary  purity  and  vivacity  of 
colour  could  not  be  obtained  from  an  aluminous  basis, 
however  dissolved,  though  it  doubtless  fixes  the  colour- 
ing particles  of  cochineal  more  durably  than  any  other 
mordant;  and  the  like  defect  was  found  to  accompany 
the  solutions  of  all  the  other  earths,  as  well  as  of  the 
metals,  tin  alone  excepted;  and  with  this  farther  disad- 
vantage, that  most  of  them  either  degraded  or  altered  the 
natural  colour  of  cochineal  very  considerably.  It  follow- 
ed, therefore,  that  a  basis  to  suit  my  purpose  must  be 
sought  for  in  the  pure  vtrhite  calx  or  oxide  of  tin,  so  dis. 
solved  or  combined,  as  to  reflect  the  cochineal  crimson 
unchanged,  and  with  the  greatest  possible  lustre.  Misled 
by  what  those  eminent  writers  Dufay,  Hellot,  Macquer, 
SchefFer,  &c.  had  advanced,  as  well  as  by  the  opinions 
of  others,  with  whom  I  had  conversed  on  this  subject,  I 
erroneously  concluded,  that  all  solutions  of  tin,  in  which 
the  nitric  acid  predominated,  would  necessarily  incline 
-the  cochineal  crimson  towards  the  yellowish  tint,  and  that 
therefore  such  solutions  ought  to  be  excluded  from  my 
experiments.  In  this  persuasion,  I  dissolved  parcels  of 
that  metal  in  almost  every  other  acid,  and  tried  them 
separately  for  dyeing  with  cochineal.  Their  several  ef- 
fects will  hereafter  be  more  particularly  stated:  at  present 
I  need  only  mention,  that  of  all  others  the  muriatic  solu- 
tion seemed  the  best  suited  to  answer  my  purpose,  as  it 
both  fixed  and  reflected  the  pure  crimson  or  rose  colour  of 


342  Philosophy  of  Permanent  Colour s^ 

the  cochineal  unchanged,*  and  with  the  utmost  brightness. 
To  produce  a  scarlet,  therefore,  it  was  only  necessary  to 
superadd,  and  intimately  combine  with  this  crimson  or 
rose  colour,  a  suitable  portion  of  a  lively  golden  yellow, 
capable  of  being  properly  fixed  and  reflected  by  the  same 
basis.  Such  a  yellow  I  had  previously  discovered  in  the 
quercitron  bark,  (which  will  be  the  subject  of  a  future 
chapter,)  and  also  in  what  is  improperly  called  young 
fustic,  (Rhus  Cotinus,  Linn.)  though  its  colour  was  less 
bright,  and  less  durable,  than  that  of  the  quercitron  bark. 
This  last  had  also  the  advantage  of  being  not  only  the 
brightest,  but  the  cheapest  of  all  yellows,  since  one 
pound  of  the  bark  in  powder,  which  cost  but  three  pence 
farthing,  dyed,  with  a  sufficient  quantity  of  muriate  of 
tin,  between  thirty  and  forty  pounds  weight  of  woollen 
cloth  of  a  full  bright  golden  yellow;  and  this  being  after- 
wards dyed  in  the  same  liquor,  with  one-fourth  less  of 
cochineal  than  what  is  usually  employed,  acquired  a  scar- 
let equal  in  beauty  and  durability  to  any  which  is  usually 
given  by  the  ordinary  means,  with  a  full  proportion  of 
cochineal;  and  such  were  the  general  results  of  a  great 
number  of  experiments. 

The  quantity  of  muriatic  solution  of  tin  necessary  to 
dye  a  given  quantity  of  scarlet  in  this  way,  seemed  to 
me  at  that  time  to  depend  on  the  proportion  of  metal 
contained  in  it,  and  this  last  to  depend  on  the  strength 
of  the  acid  used  for  this  purpose.f  That  which  I  employ- 

*  It  must  be  observed,  that  when  in  this  and  other  places  I  men- 
tion the  crimson  colour  as  produced  by  cochineal  upon  a  tin  basis, 
I  mean  a  colour  much  more  lively  and  beautiful  than  the  crim- 
son dyed  from  cochineal  upon  an  aluminous  basis.  The  former 
might,  perhaps,  with  more  propriety,  be  denominated  a  rose  co- 
lour. 

t  I  have  since  ascertained,  by  decisive  experiments,  that  muri- 
atic acid,  which  has  only  dissolved  one-half  of  the  portion  of  tin 


Philosophy  of  Permanent  Colours,  34S 

ed,  and  which  I  bought  at  the  price  of  38^.  per  112lbs. 
or  about  four- pence  per  pound,  dissolved  in  a  strong  sand- 
heat,  one-third  of  its  weight  of  granulated  tin;  and  this 
solution  would,  with  the  proportions  of  cochineal  and 
bark  before  mentioned,  dye  about  ten  times  its  weight  of 
cloth  of  a  good  scarlet  colour. 

I  have  said  that  three  pounds  of  muriatic  acid,  which 
cost  but  one  shilling,  might  be  made  to  dissolve  a  pound 
of  tin,  which  would  require  eight  pounds  of  single  aqua- 
fortis to  dissolve  it;  and  this  quantity  of  aqua-fortis,  at 
at  the  rate  of  8c/.  per  lb.  would  cost  Ss.  4d.,  so  tliat  on 
each  pound  of  tin  dissolved  by  muriatic  acid,  instead  of 
the  nitric,  I  calculated  a  saving  of  4^.  4d,  The  muriatic 
acid,  therefore,  which  M.  Beaume  had  styled  the  true 
dissolvent  of  tin,  ("  le  vrai  dissolvant  de  I'Etain,") 
seemed  also  to  be  of  all  others  the  cheapest;  and  with 
this  further  advantage,  that  a  solution  made  by  it  was  as 
transparent  and  colourless  as  the  purest  water,  and  capa- 
ble of  being  preserved  for  many  years,  in  vessels  closely 
stopped,  without  the  least  alteration,  while  the  dyers' 
nitro- muriatic  solution  of  tin  or  spirit  becomes  turbid  or 
gelatinous  very  speedily,  and  even  in  a  very  few  days,  if 
the  weather  be  warm. 

I  may  add  also,  that  the  muriatic  solution  of  tin  seem- 
ed  to  exalt  the  colours  both  of  the  quercitron  bark  and 
of  cochineal,  more  than  any  other. 

I  perceived,  moreover,  another  advantage  resulting 
from  this  new  method  of  dyeing  scarlet,  by  a  saving  of 
all  the  tartar  employed  in  tlie  old.  Before  I  began  my 
experiments  on  this  subject,  I  had  endeavoured  to  learn 

which  it  may  be  made  to  dissolve,  will  go  as  far  as  an  equal  quan- 
tity of  acid  which  has  been  saturated  with  the  metal,  and  that  the 
effects  of  the  former  are  in  every  other  respect  better  than  those  of 
the  saturated  solution,  so  that  this  last  is  at  best  an  useless  expen- 
diture of  one-half  of  the  tin  which  it  contains. 


344  Philosophy  of  Permanent  Colours* 

the  purpose  which  tartar  was  intended  to  answer  in  the 
usual  process  for  dyeing  scarlet;  but  having  obtained  no 
satisfactory  answer  on  this  point,  I  doubted  of  its  pro- 
ducing any  good  effect,  and  therefore  omitted  it  in  my 
first  trials;  and  as  they  succeeded,  I  also  omitted  it  in  all 
the  others. 

By  these  facts  and  ideas  I  was  led  to  believe  that  I 
had  made  discoveries  likely  to  produce  very  important 
national  benefits:  and  I  particularly  calculated  in  the  first 
instance  a  gain  of  about  12i  per  cent,  upon  the  whole 
quantity  of  cochineal  consumed  in  Great  Britain,  by  that 
part  of  its  colouring  matter,  which  I  proposed  to  extract 
by  the  help  of  potash,  or  soda,  and  which  I  supposed  to 
have  been  before  always  lost. 

Besides  this,  I  computed  that  a  saving  of  25  per  cent, 
upon  all  the  cochineal  used  in  Great  Britain  for  dyeing- 
scarlet,  aurora,  and  orange  colours,  would  result  from 
my  plan  of  obtaining  from  the  quercitron  bark  so  much 
yellow  as  was  required  for  the  composition  of  those  co- 
lours with  the  cochineal  crimson,  instead  of  converting 
any  part  of  this  last  more  costly  colour  into  a  yellow.  And, 
lastly,  I  calculated  other  savings,  equal  at  least  to  20,000/. 
annually,  in  the  article  of  tartar,  (acidulated  tartrite  of 
potash,)  and  in  what  the  muriatic  solution  of  tin  was 
likely  to  cost  less  than  that  which  is  commonly  used  for 
the  purposes  in  question. 

With  this  opinion  of  the  importance  of  my  discoveries 
on  ihis  subject,  I  gave  an  account  of  them,  as  well  as  of 
an  improvement  in  the  black  dye,  (which  will  be  here- 
after explained,)  to  the  right  honourable  the  lords  of  the 
committee  of  his  majesty's  privy  council,  appointed  for 
the  consideration  of  all  matters  of  trade,  &c.  (of  which 
committee  the  late  earl  of  Liverpool  was  president),  and 
their  lordships,  with  a  laudable  solicitude  for  the  public 
welfare,  were  pleased,  by  an  order,  bearing  date  at  White- 


Philosophy  of  Permanent  Colours*  345 

hall,  the  18th  of  September,  1787,  to  refer  the  same  to 
"  six  capital  dyers,  named  in  the  said  order,  who  were 
desired  to  inquire  into  the  facts  respecting  the  said  im- 
portant discoveries  in  the  black  and  scarlet  dyes;"  and 
afterwards  "  to  report  to  the  committee  their  opinion  of 
the  merits  and  utility"  thereof. 

It  was  not,  however,  until  the  22d  of  January  follow- 
ing, that  an  experiment  relating  to  the  scarlet  dye  was 
made  at  the  dye-house  of  Messrs.  Goodwin,  Piatt,  and 
Co.,  Bankside,  South wark.  Considering,  on  that  occa- 
sion, how  much  practical  operators,  in  all  the  arts,  are 
inclined  to  distrust  improvements  offered  by  speculative 
men  upon  the  grounds  of  theory  or  philosophical  reason- 
ing, I  was  desirous  of  making  my  first  trial,  under  the 
most  favourable  circumstances,  in  order  that  by  its  sig- 
nal success,  I  might  effectually  obviate  the  effect  of  any 
unfavourable  prepossessions  in  the  minds  of  those  who 
were  to  report  on  the  merits  of  my  discoveries.  For  this 
purpose  I  prepared  a  large  quantity  (near  lOOlbs.)  of  the 
muriatic  solution  of  tin;  and  in  order  that  the  acid  might 
be  perfectly  saturated  with  the  metal,  I  added  an  over- 
proportion  of  the  latter,  and  kept  both  at  the  boiling 
point,  by  means  of  a  sand  heat,  for  the  space  of  three 
days  and  nights.  In  this  way  I  obtained  a  solution  per- 
fectly colourless,  of  a  very  pungent  smell,  and  so  highly 
volatile  and  elastic,  that  it  was  impossible  to  prevent  its 
escape  from  the  vessels  in  which  it  was  contained,  how- 
ever closely  stopped.  It  was,  in  fact,  but  little  different 
from  the  fuming  liquor  of  Libavius,  in  which  dry  mu- 
riatic acid  is  saturated  with  tin;  but  this  complete  satu- 
ration, instead  of  proving  beneficial,  as  I  had  expected, 
became  an  obstacle  to  my  success;  because  the  union 
between  the  acid  and  the  metal  was  thereby  rendered  so 
intimate  and  powerful,  that  the  affinities  of  the  cloth  and 
the  colouring  matter  of  the  bark  could  not  overcome  it, 

Vol.  I.  2  X 


346  Philosophy  of  Permanent  Colours. 

except  in  a  degree  too  small  to  afford  a  sufficient  basis 
for  the  cochineal  colour;  and  farther  quantities  of  the 
solution  being  therefore  added,  to  supply  tjjiis  deficiency, 
(from  an  erroneous  notion  respecting  the  cause  of  it,)  the 
texture  of  the  cloth  was  by  these  additions  greatly  weak- 
ened and  injured. 

Two  pieces  of  long  baize,  weighing  together  188lbs, 
had  been  chosen  as  the  objects  of  this  experiment.  I  had 
before  observed  in  my  private  trials,  that  the  colour  gene- 
rally proved  most  lively  when  given  with  a  full  propor- 
tion of  the  muriate  of  tin;  and  also  that  the  colouring 
matter  of  the  cochineal  was  most  completely  imbibed 
and  taken  up  out  of  the  dyeing  liquor  by  the  cloth, 
when  the  whole  portion  of  the  solution  of  tin,  instead  of 
being  applied  at  different  times,  was  boiled  up  at  once 
with  the  quercitron  bark;  an  effect  the  more  desirable  for 
me  at  that  time,  because  I  intended  to  employ  a  very 
small  proportion  of  cochineal,  and  therefore  wished  to 
leave  as  little  as  possible  of  its  colouring  matter  behind, 
floating  in  the  dyeing  liquor,  especially  as  it  would  be 
difficult  properly  to  estimate  the  exact  quantity  remain- 
ing therein. 

For  these  reasons,  I  took  a  large  portion  of  the  solu-  - 
tion  of  tin,  i.  e.   161bs.  weight  for  the  two  pieces  of 
baize,  and  threw  the  whole  of  it  at  once,  with  five 
pounds  of  powdered  quercitron  bark,  into  a  suitable  tin 
vessel y^  properly  filled  with  water  a  little  warmed,  into 

*  For  a  considerable  number  of  years,  the  scarlet  colour  had 
been  constantly  dyed  in  vessels  made,  or  consisting  wholly  of  block 
tin.  Very  lately,  however,  it  has  been  found  that  copper  bottoms 
might  be  given  to  these  vessels  without  injuring  the  colour,  and 
with  a  great  saving  of  expense,  as  they  prove  much  more  durable, 
and  the  copper  is  but  little  acted  upon  when  secluded  from  atmo- 
spheric air,  by  being  covered  with  water,  &c.;  and  even  in  the  dye- 
ing operation,  the  acids  arc  more  disposed  to  exert  their  action 


Philomphy  of  Permanent  Colours,  347 

which  the  pieces  of  baize  (previously  moistened)  were 
soon  after  put,  and  turned  as  usual  over  a  winch  through 
the  liquor  (which  was  made  to  boil)  for  the  space  of  an 
hour,  when  they  were  both  taken  out  and  rinced  in  clean 
water,  the  dyeing  vessel  being  at  the  same  time  emptied, 
and  then  filled  again  with  warm  water  for  the  remaining 
part  of  the  operation.  The  baize  had,  in  this  first  boiling, 
acquired  a  very  bright  golden  yellow,  though  but  about 
one.fortieth  part  of  its  weight  of  bark  was  employed;  and 
I  had  expected,  from  what  had  before  happened  in  my 
own  particular  experiments,  that  it  would  have  been  so 
fully  impregnated  by  the  metallic  basis,  as  to  want  no 
farther  addition  of  the  muriate  of  tin  in  the  second  part 
of  the  process.  To  secure  myself,  however,  against  a 
disappointment  on  this  point,  I  cut  off  a  bit  fi-om  one 
of  the  pieces,  and  boiling  it  in  a  small  pipkin  with  water, 
and  a  little  cochineal,  I  saw  with  great  concern  that  the 
fibres  of  the  cloth  were  very  far  from  having  imbibed 
enough  of  the  oxide  of  tin  to  fix  and  raise  the  cochineal 
colour;  and  that  a  farther  portion  of  the  solution  would 
be  absolutely  necessary  for  this  purpose.  The  cause,  in- 
deed, of  this  disappointment,  was  only  ascertained  by 
subsequent  experiments,  though  it  might  have  been  con- 
jectured at  that  time,  as  the  water  into  which  the  solu- 
tion of  tin  had  been  poured  in  the  dying  vessel,  did  not 
decompose  any  part  of  it,  or  become  in  the  slightest  de- 
gree milky  or  turbid,  as  it  does  with  other  solutions  of 
of  that  metal;  and  the  attraction  of  the  woollen  cloth  was 
evidently  much  too  feeble  to  separate  and  attach  to  itself 
any  part  of  the  oxide  of  tin,  excepting  that  which  liad 
united  with  the  colouring  matter  of  the  bark,  and  by  this 
additional  affinity  became  fixed  in  the  wool  as  the  basis 


upon  the  tin  of  which  the  upper  part  of  the  vessel  consists,  and 
upon  the  cochineal  and  the  cloth,  than  on  the  copper  bottom. 


348  Philosophy  of  Permanent  Colours. 

of  that  golden  yellow  which  it  had  received,  as  already 
mentioned;  whilst  the  other  and  greater  part  of  the  oxide 
remained  in  the  water,  (combined  with  the  muriatic 
acid,)  and  ^vas  thrown  away  with  it  after  the  first  boil- 
ing, but  unfortunately  not  without  having  previously 
weakened  the  fibres  of  the  wool  by  its  corrosive  proper- 
ty, of  which  I  had  no  suspicion,  until  it  became  manifest 
in  the  second  part  of  the  operation.  For  this,  five  pounds 
of  cochineal  were  put  into  the  dyeing  vessel,  with  six 
pounds  more  of  the  muriate  of  tin,  and  being  well  mix- 
ed in  UK  water,  the  two  pieces  of  baize  were  put  into 
the  liquor,  and  dyed  therein  for  about  fifteen  minutes, 
when  the  colour  not  seeming  to  rise  properly,  four  pounds 
more  of  the  solution  of  tin,  and  one  pound  of  cochineal, 
were  added;  and  the  dyeing  was  continued,  until  it  ap- 
peared soon  after  that  the  texture  of  the  cloth  was  greatly 
injured  by  the  muriate  of  tin,*  which  seemed  in  this,  as 
well  as  in  subsequent  trials,  to  have  a  much  stronger  and 
more  corrosive  action  upon  the  fibres  of  wool  than  other 
solutions  of  that  metal,  though  before  that  time  I  had 
always  been  persuaded  that  it  would  on  the  contrary 
have  acted  more  mildly  in  tliis  respect  than  the  ordinary 
dyer's  solution  or  spirit;  and  indeed  I  had  been  led  to 
this  persuasion  by  the  concurrent  opinions  of  several 
very  eminent  chemists,  who  had  all  represented  the  nir 

*  Subsequent  experiments  have  proved,  that  if  my  purpose  of 
employing  the  yellow  of  the  quercitron  bark,  in  conjunction  with  a 
rose  colour  from  cochineal,  would  have  allowed  me  to  add  the 
usual  portion  of  tartar  on  this  occasion,  the  injury  sustained  by  the 
cloth  might  have  been  completely  obviated;  for  the  acid  of  the  tar- 
tar, like  every  other  acid  which  I  have  tried,  greatly  corrects  this 
hurtful  sort  of  action,  which  the  muriate  of  tin,  when  employed 
alone,  exercises  on  wool  or  woollen  stuffs.  The  tartar  would,  more- 
over, have  rendered  the  muriate  of  tin  more  susceptible  of  decom- 
fiositioriy  by  affording  a  portion  of  superfluous  or  uncombined  actdy 
so  that  less  of  the  muriate  of  tin  would  have  been  sufficient. 


Philosophy  of  Permanent  Colours,  349 

trie  acid  as  exerting  a  stronger  and  more  corrosive  ac- 
tion than  the  muriatic  upon  animal  substances.  Even 
that  very  excellent  chemist  Berthollet  has  observed,  in 
tenth  volume  of  the  Ann.  de  Chimie,  published  so  late- 
ly as  the  month  of  August  1791,  and  after  he  had  been 
particularly  employed  in  examining  the  effects  of  the 
different  acids  upon  wool  and  silk,  that  "  I'acide  sulphu- 
rique  et  I'acide  muriatique  exercent  une  action  moins 
vive  sur  les  substances  animales  que  I'acide  nitrique  suf- 
fisamment  concentre."  And  this  doubtless  is  true  of  these 
acids  acting  merely  as  acids;  but  very  different  properties 
appear  to  result  from  their  combinations  with  metals, 
and  metallic  substances;  among  which,  the  metallic  solu- 
tions by  muriatic  acid  seem  generally  more  corrosive 
than  those  made  by  any  other.  This  is  particularly  true 
of  the  muriates  of  mercury,  silver,  lead,  bismuth,  and 
antimony,  as  well  as  that  of  tin;  but  the  corrosive  nature 
of  this  last,  and  the  difficulty  of  decomposing  it,  seem  to 
be  increased,  in  proportion  as  the  muriatic  acid  is  more 
completely  saturated  or  combined  with  a  greater  portion 
of  the  metal.  It  is  indeed  true,  that  the  proportion  of  so- 
lution of  tin  used  in  the  foregoing  experiment,  was  much 
greater  than  I  had  ever  before  employed,  as  it  amounted 
to  26lbs.,  and  contained  above  six  pounds  of  the  metal, 
which  is  four  times  as  much  as  would  suffice  (dissolved 
by  a  mixture  to  be  hereafter  explained)  for  the  same 
weight  of  cloth.  But  still  I  am  persuaded,  that  an  equal 
quantity  of  any  other  solution  of  tin  would  not  have  in- 
jured the  like  quantity  of  cloth  in  an  equal  degree;  and 
being  thus  made  sensible  of  the  danger  that  must  attend 
the  use  of  a  mordant  so  corrosive,  I  was  convinced  of 
tJie  expediency  of  searching  for  one  more  harmless  in 
this  respect,  though  it  certainly  is  very  possible,  with 
proper  care,  to  employ  the  muriate  of  tin  (containing  a 
smaller  proportion  of  the  metal)  so  as  to  produce  all  the 


350  Philosophy  of  Permanent  Colours. 

good  effects  which  I  had  expected  from  it,  without  any 
injury  to  the  cloth,  as  I  have  found  by  a  multitude  of 
experiments  since,  as  well  as  before,  that  of  the  22d  of 
January,  1787. 

Whence  this  corrosive  property  of  the  muriate  of  tin 
arises,  may  become  a  subject  of  future  inquiry.  At 
present,  I  shall  only  observe,  that  in  some  experiments 
which  I  made,  with  a  hope  of  correcting  it,  I  constantly 
found  this  saturated  muriate  of  tin  possessing  a  strong 
attraction  for  oxygene,  and  that  by  absorbing  it,  as  it  did 
from  various  matters,  its  corrosive  property  was  always 
greatly  diminished.  This  led  me  to  oxygenate  the  mu- 
riatic solution  of  tin,  by  putting  a  very  little  manganese 
into  it,  or  rather  by  dissolving  tin  with  a  very  little  man* 
ganese  in  muriatic  acid;  but  though  the  solution  made  in 
this  way  appeared  less  corrosive,  it  contained  a  small 
portion  of  the  manganese,  which  darkened  the  cochineal 
colour,  making  it  incline  towards  a  purple. 

I  afterwards  oxygenated  the  muriatic  acid,  by  mixing 
it  with  about  one-third  less  than  its  own  weight  of  the 
nitric,  and  with  this  I  made  a  solution  of  tin;  which  ap- 
pearing to  be  no  more  corrosive  than  the  common  dyers' 
spirit,  and  not  changing  the  cochineal  crimson  towards 
the  yellow  hue,  I  was  hastily  induced  to  venture  with  it 
upon  another  trial  at  the  dye-house  of  Messrs.  Goodwin 
and  Co.,  a  few  weeks  after  the  first.  It  was,  however, 
made  only  on  one  piece  of  baize,  weighing  about  ninety 
pounds,  which  I  caused  to  be  boiled  with  about  eight 
pounds  of  this  murio-nitric  solution  of  tin,  and  two 
pounds  and  one  half  of  powdered  quercitron  bark.  This 
mordant,  however,  acted  very  feebly,  or  rather  failed,  in 
exalting  the  yellow  colour  of  the  bark,  which  took  but 
very  slowly  on  the  baize,  and  never  rose  much  higher 
than  a  stra^v  colour,  even  after  two  hours  boiling;  when 
a  considerable  quantity  of  yellow  colour,  united  to  the 


Philosophy  of  Permanent  Colours.  351 

calx  of  tin,  evidently  remained  floating  in  the  water, 
not  because  the  calx  was  too  intimately  combined  with 
the  acid  solvent,  as  in  the  first  experiment, — but  because, 
for  want  of  a  sufficient  attraction  between  them,  it  had 
been  almost  wholly  decomposed  as  soon  as  they  were 
put  into  water:  and  in  boiling,  it  fixed  itself  with  the 
bark  colour  upon  the  cloth  very  sparingly,  superficially, 
and  slowly.  This  also  happened  in  the  second  part  of  the 
operation;  for  which  three  pounds  of  cochineal,  and  six 
of  this  murio- nitric  solution  of  tin,  were  at  first  employ- 
ed; but  the  colour  not  rising  sufficiently,  another  pound 
of  cochineal,  with  four  pounds  more  of  the  same  solution, 
were  added  to  the  liquor  in  which  the  cloth  was  dyed  for 
the  space  of  two  hours,  when  a  considerable  part  of  the 
colour  still  appeared  floating,  but  not  dissolved,  in  the 
water.  So  much,  indeed,  had  been  applied  to  the  cloth,  as 
to  give  it  a  passable  scarlet  colour,  which,  however,  had 
penetrated  but  very  little  into  its  substance,  so  that  the 
cloth  seemed,  as  Mr.  Goodwin  observed,  to  have  been 
rather  painted  than  dyed.*  It  was,  however,  generally 

*  According  to  my  best  recollection,  the  solution  of  tin  employ- 
ed for  this  experiment  had  been  made  eight  or  ten  days  before  it 
was  so  employed,  and  during  this  interval  the  metal  had  probably 
become  too  much  oxygenated:  and  it  had  moreover  the  disadvan- 
tage of  being  used  without  the  aid  of  tartar,  which  by  its  acid  seems 
to  enable  the  oxide  of  tin,  as  well  as  the  cochineal  colour,  to  pene- 
trate and  unite  more  copiously  with  the  fibres  of  wool.  I  very  lately 
(Nov.  1812),  mixed  three  ounces  of  strong  nitric  acid  of  the  speci- 
fic gravity  of  1500,  with  seven  ounces  of  muriatic  acid  of  the  spe- 
cific gravity  of  about  1165.  The  mixture,  as  is  usual,  effervesced, 
and  assumed  for  a  short  space  of  time  a  deep  red  colour.  In  this 
mixture  diluted  with  six  ounces  of  water,  I  dissolved  two  ounces 
of  fine  granulated  tin,  and  the  next  day  employed  a  suitable  portion 
of  it,  with  cochineal  and  cream  of  tartar,  to  dye  a  small  piece  of 
broad-cloth.  I  observed,  on  putting  the  solution  of  tin  into  the  wa- 
ter, that  it  collected  therein  like  small  loose  dispersed  curds^  which, 
however,  by  a  little  boiling  with  the  tartar,  were  completely  dissolv- 


352  Philosophy  of  Permanent  Colours. 

agreed,  after  a  particular  examination,  that  notwithstand- 
ing the  great  length  of  time  in  which  the  baize  had  been 
boiled  with  a  very  large  proportion  of  the  solution  of  tin, 
{L  e,  181bs.  for  a  single  piece  weighing  but  901bs.),  its 
texture  had  not  received  the  smallest  injury;  so  that  in 
this  respect  my  last  experiment  proved  less  expensive 
than  the  first,  though  both  together  cost  me  nearly  30/. 

As  this  murio-nitrate  of  tin,  though  exempt  from  the 
defects  of  the  muriatic  solution,  had  failed  through  others 
of  a  very  opposite  nature,  I  was  induced  to  mix  much 
greater  proportions  of  nitric  with  the  muriatic  acid  for 
dissolving  tin,  in  order  to  see  how  much  of  the  former 
could  be  used  in  this  way,  without  so  far  yellowing  the 
cochineal  crimson  as  to  preclude  the  use  of  any  of  the 
quercitron  yellow  in  the  dyeing  of  scarlet,  an  effect  which 
I  still  expected  from  the  nitric  acid,  when  used  in  a  very 
large  proportion;  but,  to  my  great  surprise,  I  could  dis- 
cover no  such  effect,  even  when  I  had  dissolved  the  me- 
tal in  nitric  acid  alone.  At  first  I  suspected  some  im- 
purity in  the  acid  which  had  been  employed;  but  having 

ed,  and  the  cloth  being  put  into  this  liquor  with  a  part  of  the  cochi- 
neal, and  boiled  in  it  as  usual,  and  afterwards  dyed  with  the  re- 
mainder of  the  cochineal  and  more  of  the  solution  of  tin  and  tartar, 
imbibed,  contrary  to  my  expectation,  a  very  drigAt  good  scarlet,  eX' 
cepting  that  it  inclined  a  little  too  much  to  the  orange  tint.  In  this 
case  the  colour  had  penetrated  and  united  itself  to  the  cloth  as  ex- 
peditiously as  with  the  solution  of  tin  commonly  employed  by  the 
dyers,  and  without  any  such  difficulty  as  I  had  experienced  in  my 
second  experiment  at  the  dye-house  of  Messrs.  Goodwin  and  Co.; 
an  advantage  which  must,  as  I  think,  have  resulted  from  my  having 
in  this  latter  trial  employed  the  solution  of  tin  when  recently  made, 
and  in  conjunction  with  the  tartar,  which  was  omitted  in  the  former: 
but  I  will  endeavour  to  ascertain  the  truth  on  this  point  by  future 
trials  with  the  same  solution,  after  it  has  been  kept  during  various 
longer  periods,  and  also  with  and  without  the  co-operation  of  tar- 
tar, and  mention  their  results  in  a  postscript  to  my  second  vo- 
lume. 


Philosophy  of  Permanent  Colours.  353 

procured  a  fresh  supply,  and  ascertained  its  purity  by  the 
proper  means,  I  still  found  that  tin  dissolved  by  it  had 
not  the  least  tendency  to  change  the  cochineal  crimson 
towards  a  yellowish  or  scarlet  hue;  and  that  this  effect^ 
in  the  usual  way  of  dyeing  that  colour,  resulted  wholly 
from  the  tartar,  (acidulated  tartrite  of  potash,)  which  is 
always  employed  at  the  same  time.  This  fact  I  ascertained 
by  repeated  and  varied  experiments,  in  which  I  constantly 
found  that  cochineal,  with  the  dyers'  common  solution 
of  tin,  and  even  with  that  made  by  nitric  acid  only,  would 
produce  nothing  but  a  crimson  without  tartar;  and  that 
cochineal,  with  tartar,  would  produce  a  scarlet,  not  only 
with  these  last  mentioned  solutions,  but  also,  and  equally 
well,  with  the  muriatic  solution  of  that  metal;  and  there- 
fore, that  every  thing  which  had  been  taught  and  believed 
to  the  contrary  was  repugnant  to  truth.  And  here  I  can- 
not  conceal  my  wonder,  that  an  error  of  so  much  conse- 
quence, and  so  destitute  of  all  foundation,  should  have 
been  propagated  and  confirmed  by  so  many  acute  reason- 
ers  and  sagacious  observers  in  other  respects;  for,  besides 
those  eminent  writers  already  mentioned,  Mr.  Poerner 
has  more  recently  adopted  and  propagated  the  same  er- 
ror, after  making  a  great  number  of  experiments,  several 
of  which,  if  they  had  been  duly  considered,  would  have 
taught  him  the  truth  on  this  subject.*  This  also  was 
even  more  lately  done  by  M.  Berthollet,  in  his  Elemens 
de  I'Art  de  la  Teinture,  where,  to  adopt  the  words  of 
Dr.  Hamilton's  translation,  he  says,  *'  Tartar,  as  we  have 
seen,  gives  a  deeper  ^nd  more  rosy  hue  to  the  colouring 
piatter  of  cochineal,  precipitated  by  the  solution  of  tin.  It 
moderates  the  action  of  the  nitro- muriatic  acid,  which 
tends  to  give  scarlet  an  orange  cast,  though  this  orange 
cast  is  not  to  be  seen  in  the  precipitate  produced  by  the 

*  See  Instruction  sur  I'Art  de  la  Teintnre,  he  a  Paris.  179 1 
V©L.  I.  2  Y 


354  Philosophy  of  Permanent  Colours:. 

solution  of  tin,  which  is  on  the  contrary  of  a  fine  red.  It 
is  probable  that  the  solution  of  tin  gives  scarlet  an  orange 
tinge,  by  means  of  the  action  the  nitro- muriatic  acid  ex- 
erts on  the  wool,  which,  as  well  as  all  other  animal  sub- 
stances, it  has  the  property  of  turning  yellow."* 

"  Thus  (adds  he,)  by  putting  more  of  tartar  into  the 
reddening,  a  deeper  and  fuller  scarlet  may  be  obtained; 
and  on  the  contrary,  the  scarlet  may  be  rendered  more 
inclining  to  orange  by  omitting  this  ingredient."  And  he 
concludes  the  chapter  by  repeating  this  doctrine. 

Here  then  it  is  manifest,  that  the  nitro-muriate  of  tin 
and  the  tartar  are  each  supposed  to  produce  effects  dt- 
rectly  contrary  to  those  which  are  really  produced  by 
them,  the  effects  of  each  being  ascribed  to  the  other;  a 
mistake  capable  of  producing  much  disappointment  and 
detriment.! 

*  It  is  true  that  nitric  acid  alone  makes  wool,  &c.  yellow;  but 
wool  or  clotli,  boiled  with  nitro-muriate  of  tin,  as  a  preparation  for 
scarlet,  remains  perfectly  white,  if  no  colouring  is  mixed  with  it,  as 
is  well  known. 

t  M.  BerthoUet,  with  his  usual  and  becoming  cancfowr,  has,  in  the 
last  edition  of  his  Elements,  &c.  admitted  the  error  into  which  he 
had  fallen,  in  common  with  all  others,  on  this  subject,  and  the  truth 
of  my  observations  respecting  it.  ''  On  avoit,  (says  he,)  dans  la  pre- 
miere edition  de  ces  elemens,  attribue  au  tartre  la  propriete  de  don- 
ner  line  nuance  plus  foncee  et  plus  rosee  aux  parties  colorantesde 
la  cochenille:  cette  opinion  pouvait  meme  etre  regardee  comme 
generale;  mais  Bancroft  Va  combattue  avec  raison:  il  pretend  que  si 
Ton  supprime  le  tartre,  on  a  une  couleur  craraoisie;  que  le  tartre 
donne  naissance  a  un  tartrite  d'etain  insoluble,  qui  fait  avec  la  co- 
chenille une  couleur  jaune;  que  Tecarlate  ordinaire  est  un  melange 
d*un  quart  de  cette  couleur  jaune  et  de  trois  quarts  ou  un  peu  plus 
de  la  couleur  cramoisie  que  donne  la  cochenille  avec  la  dissolution 
d'etain,"  &e.  And  after  mentioning  my  proposal  for  obtaining  the 
yellow  part  of  the  scarlet  colour  from  the  quercitron  bark,  rather 
than  from  cochineal,  he  gives  an  account  of  three  experiments 
which  he  had  made  by  dyeing  cloth  with  cochineal  and  a  solution 
of  tin;  for  two  of  which  he  also  employed  tartar  in  the  ordinary* 


Philosophy  of  Permanent  Colours,  355 

Having  made  myself  certain  that  the  dyers'  spirit,  or 
nitro- muriatic  soluticwi  of  tin,  without  tartar,  would  only 
dye  a  crimson  with  cochineal,  I  was  induced  to  make  an 
experiment  therewith,  instead  of  the  muriate  of  tin,  at  the 
dye-house  of  the  late  Mr.  Seward,  in  Gos well- street,  and 
with  views  similar  to  those  which  directed  the  experi- 
ments before  made  at  the  dye-house  of  Messrs.  Goodwin 
and  Co.  A  piece  of  baize  was  accordingly  boiled  one 
hour  and  a  quarter  with  the  usual  portion  of  nitro-muri- 
atic  solution  of  tin,  (which  had  been  prepared  by  Mr. 
Seward,)  and  with  about  one-fortieth  of  its  weight  of 
quercitron  bark,  without  any  tartar:  after  which  it  was 
taken  out  dyed  of  a  bright  yellow,  though  paler  than  it 

and  in  a  double  proportion:  and  he  found  that  in  proportion  to  the 
quantity  of  tartar  employed,  the  colour  inclined  to  the  yellow  tint, 
whilst  that  without  tartar  "  avoit  couleur  vineuse  et  moins  vive," 
&c.  He  adds,  "  il  est  done  vrai  que  le  tartre  fait  incliner  au  jaune 
la  couleur  de  la  cochenille,  et  qu'il  produit  d*autant  plus  cet  eifet, 
que  la  proportion  en  est  plus  grande,"  &c.  Elemens,  torn.  ii.  p.  179, 
180. 

I  must  observe,  however,  that  the  explanation  here  given  by  M. 
Berthollet,  of  my  conclusions  in  regard  to  the  effects  of  tartar  in  the 
dyeing  of  scarlet,  is  not  quite  correct.  I  have  never  intended  to  de- 
cide, that  the  acid  of  tartar  formed  an  insoluble  tartrite  of  tin,  and 
that  this  tartrite  changed  the  colour  of  a  fiart  of  the  cochineal  to  a 
pure  yellow,  and  thereby  gave  to  the  other  part  a  scarlet  tint; 
though  I  have  in  fact  supposed  this  as  an  ultimate  effect  to  result 
from  the  action  of  tartar.  But  I  intended  to  leave  it  undecided,  whe- 
ther the  acid  of  tartar  acted  conjointly  with  the  other  acids  and  the 
tin,  or  separately  with  the  metal,  in  producing  a  scarlet  instead  of 
the  rose  colour,  which  would  have  been  produced  without  it;  and 
though  1  supposed  the  amount  of  this  change  to  be  equivalent  to  a 
conversion  of  nearly  one-fourth  of  the  cochineal  colour  to  a  yellotv, 
yet  I  did  not  assume  that  the  change  in  question  had  been  operated 
or  effected  in  a  fourth  or  any  other  part  exclusivehj^  rather  than  on 
the  whole  collectively.  Indeed,  I  have  never  found  the  tartrite  of 
tin,  even  when  employed  alone  with  cochineal,  able  to  render  the 
colour  yellowy  though  it  produces  a  very  yellowish  scarlet. 


i56  Fhilosophy  of  Permanent  Colours, 

would  have  been  with  the  muriate  of  tin.  The  baize  be- 
ing rinced,  and  the  dyeing  vessel  emptied,  and  then  filled 
a  second  time  with  clean  water,  about  four-fiiths  of  the 
cochineal  usually  employed  for  the  like  quantity  of  baize, 
and  a  farther  suitable  proportion  of  the  solution  of  tin, 
were  put  into  it,  and  the  baize  being  dyed  therein,  as 
usual,  took  what  was  allowed  to  be  a  good  scarlet.  Mr. 
Seward,  however,  did  not  seem  so  fully  convinced,  as  I 
had  expected,  of  the  advantage  of  compounding  a  scarlet 
in  this  way  from  the  cochineal  crimson  and  quercitron  yel- 
low; and  probably  the  experiment  had  not  been  attended 
with  any  very  manifest  success,  or  saving  of  cochineal, 
because  the  nitro-muriatic  solution  of  tin  which  had  pro- 
duced but  a  pale  yellow  with  the  quercitron  bark,  had 
also  acted  more  feebly  in  raising  or  exalting  the  cochineal 
colour  than  it  usually  does  when  assisted  with  tartar, 
which  consists  of  a  portion  of  vegetable  alkali  combined 
with  an  excess  of  its  own  peculiar  acid;  and  therefore, 
whenever  it  is  mixed  with  a  solution  of  tin  by  any  of  the 
mineral  acids,  the  tartar  will  be  decomposed;  because  the 
mineral  acids,  by  their  superior  attraction  for,  will  unite 
with  its  alkaline  basis,  and  disengage  an  additional  por- 
tion of  the  tartarous  acid,  which  will  then  unite  with  the 
metallic  oxide,  previously  abandoned  by  the  mineral 
acid,  and  thus  produce  a  t  art  rite  of  tin  ^  which  last,  in  the 
usual  way  of  dyeing  scarlet,  inclines  the  cochineal  crim- 
son to  the  yellow  tint,  and  at  the  same  time,  (as  I  have 
since  found,)  exalts  its  colour  more  than  the  nitro-muri- 
atic solution  of  tin  alone  would  be  able  to  do;  and  it  is 
only  this  decomposition  of  the  tartar,  that  has  obviated 
the  ill  effects  which  otherwise  must  have  resulted  from 
the  sulphuric  acid,  frequently  contained  in  the  common 
aqua-fortis  used  by  the  scarlet  dyers.* 

•This  statement,  first  made  in  1794,  respecting  the  effects  of 
tartar  with  sulphuric  acid,  is  partly  erroneous,  or  liable  to  miscon- 


Philosophy  ofPermanen t  Colours.  ^Sl 

Though  I  had  hitherto  failed  in  my  endeavours  to  com- 
pose  a  scarlet  colour  with  advantage,  so  as  to  save  that 
part  of  the  cochineal  which  appeared  to  be  misapplied,  by 
being  yellowed  in  the  usual  process,  I  had  nevertheless 
full  confidence  in  my  former  reasoning  on  this  subject, 
and  employed  myself  from  time  to  time  in  searching  after 
more  suitable  means  for  attaining  this  end.  Some  of  my 
earliest  experiments  with  a  solution,  or  rather  a  calcination 
of  tin  by  the  sulphuric  acid,  had  shown  me  that  this  pre- 
paration was  very  unsuitable  for  my  purpose,  because  it 
really  exerted  a  destructive  action  on  the  cochineal  co- 
lour, by  reducing  it  from  a  crimson  down  to  a  kind  of 
salmon  colour,  which  indeed  was  the  highest  colour  pro- 

ception:  wherever  that  acid  (the  sulphuric)  acts  upon  tin,  either 
alone^  or  with  any  mixture  containing  nitric  acid,  the  oxide  of  that 
metal,  probably  by  to©  much  oxygenation,  is  brought  into  a  state 
which  renders  it  incapable  of  producing  with  cochineal  any  thing 
better,  or  approaching  nearer  to  scarlet  than  an  orange,  or  at  most 
a  high  salmon  colour.  It  is  true,  indeed,  that  if  oil  of  vitriol  be  put 
either  into  the  scarlet  dyeing,  or  the  preparation  liquors,  immedi- 
ately after,  or  conjointly  with  the  tartar,  it  will  do  no  harm,  provi- 
ded the  quantity  be  only  sufficient  to  decomfiosc  the  tartar^  and  neu- 
tralize its  alkaline  part.  But  as  no  tartar  is  employed  by  the  dyers 
in  making  their  ordinary  solution  of  tin,  and  as  the  aqua-fortis 
used  for  that  purpose,  frequently  contains  a  little  sulphuric  acid, 
the  latter  will  have  produced  all  its  mischievous  effects  upon  the 
tin,  previously  to  the  dyeing  operation,  and  these  effects  will  not 
afterwards  be  overcome  by  the  tartar  employed  in  that  operation. 
Fortunately,  however,  the  mischief  which  might  be  produced  by  a 
little  sulphuric  acid  mixed  with  the  aqua-fortis  employed  by  the 
dyers  to  dissolve  their  tin,  is  commonly  obviated^  without  their  be- 
ing sensible  of  it,  by  their  practice  of  making  a  nitro- muriatic  acid, 
not  by  mixing  the  muriatic  simfily  with  the  nitric  acid,  but  by  adding 
to  the  latter  a  portion  either  of  sea-salt,  or  of  muriate  of  ammonia, 
cither  of  which  affords  an  alkali,  which,  by  its  stronger  affinity  for 
Ih?  sulphuric,  than  for  either  the  nitric  or  muriatic  acids,  combines 
with  and  neutralizes  the  former,  when  the  quantity  is  not  loo  great, 
and  thus  renders  it  harmless. 


358  Philosophy  of  Permanent  Colours, 

duced  on  cloth  by  dyeing  it  with  cochineal  and  sulphate 
of  tin;  I  therefore  discarded  the  use  of  sulphuric  acid  for 
dissolving  tin,  until  particular  circumstances  led  me  some 
time  after  to  dissolve  a  portion  of  it  by  the  muriatic  acid, 
combined  with  about  one- fourth  of  its  weight  of  oil  of  vi- 
triol; and  by  trying  this  solution,  I  found  that  it  produced 
very  good  effects  in  dyeing,  without  any  appearance  of  that 
corrosive  property  which  had  acted  so  mischievously  in 
the  experiments  made  with  tin,  dissolved  by  muriatic  acid 
only.  I  was  therefore  encouraged  to  make  and  try  other  so- 
lutions  of  that  metal,  by  the  same  acids,  united  in  various 
proportions;  and  have  at  length  found  reason  to  prefer  a 
solution  made  by  dissolving  after  the  rate  of  about  four- 
teen ounces  of  tin  in  a  mixture  of  two  pounds  of  oil  of 
vitriol,  (of  the  usual  strength,)  with  about  three  pounds 
of  muriatic  acid.  That  which  I  have  used  was  of  the  spe- 
cific gravity  of  nearly  1170,  and  strong  enough,  with  a 
sand-heat,  to  dissolve  one-third  of  its  weight  of  tin.  The 
muriatic  acid  should  be  first  poured  upon  a  large  quantity 
of  granulated  tin,  in  a  capacious  glass  receiver,  and  the 
oil  of  vitriol  afterwards  added  slowly;  and  these  acids  be- 
ing mixed,  should  be  left  to  saturate  themselves  with 
tin,  which  they  will  do  in  a  longer  or  shorter  time,  ac- 
cording to  the  temperature  of  tlie  atmosphere,  without 
any  artificial  heat;  but  the  solution  may  be  rapidly  pro- 
moted by  a  sand-heat. 

This  solution  contained  but  little  more  than  half  as 
much  tin  as  the  muriatic  solution  which  had  been  used 
in  the  first  experiment  made  at  the  dye-house  of  Messrs. 
Goodwin  and  Co.,  yet  the  metallic  part  of  it  existed  in  a 
state  so  much  more  suitable  for  the  purposes  of  dyeing, 
that  a  given  quantity  of  it  would  produce  much  better 
effects  than  a  like  quantity  of  muriatic  solution,  contain- 
ing nearly  twice  as  much  of  the  metal,  and  without  any 
corrosive  property,  capable  of  doing  the  least  mischief^ 


Philosophy  of  Permanent  Colours,  359 

unless  used  in  much  greater  proportions  than  ever  can  be 
wanted  for  dyeing.* 

The  murio-sulphuric  solution  of  tin,  made  in  these 
proportions,  will  be  perfectly  transparent  and  colourless; 
and  will  probably  remain  so  for  many  years,  without  be- 
coming turbid,  or  suffering  by  any  precipitation  of  the 
metal;  at  least,  none  has  appeared  in  some  which  I  have 
kept  for  more  than  three  years.  It  will  produce  full 
twice  as  much  effect  as  the  dyers'  spirit,  or  nitro-muriatic 
solution  of  tin,  with  less  than  a  third  of  the  expense.  It 
has,  moreover,  the  property  of  raising  the  colours  of,  I 
believe,  all  adjective  dyes,  more  than  the  dyers^  spirit,  and 
full  as  much  as  the  tartrite  of  tin,  without  changing  the 
natural  crimson  of  cochineal  towards  the  yellowish  hue; 
and,  therefore,  after  having  made  a  great  number  of  ex- 
periments with  it,  I  think  myself  warranted  in  strongly 
recommending  this  murio- sulphate  of  tin  for  dyeing  the 
compound  scarlet  colour  already  described,  (with  the 
cochineal  crimson  and  quercitron  yellow,)  for  which  it 
will  be  fou»d  highly  effectual  and  economical. 

For  this  species  of  scarlet  nothing  is  necessary  but  to 
put  the  cloth,  suppose  lOOlbs.  weight,  into  a  proper  tin 
vessel,  nearly  filled  with  water,  in  which  about  eight 
pounds  of  the  murio-sulphuric  solution  of  tin  have  been 
previously  mixed,  to  make  the  liquor  boil,  turning  the 
cloth  as  usual  through  it,  by  the  winch,  for  a  quarter  of  an 
hour;  tiien  turning  the  cloth  out  of  the  liquor,  to  put  into 
it  about  four  pounds  of  cochineal,  and  two  pounds  and  a 
half  of  quercitron  bark  in  powder,  and  having  mixed 
them  well,  to  return  the  cloth  again  into  the  liquor,  mak» 

*  Since  my  first  edition  of  this  volume  was  published,  I  have  as- 
certained that  even  the  proportion  of  tin  here  mentioned  is  unne- 
cessarily great,  and  that  equally  good  effects  may  be  obtained  with 
the  same  quantity  of  acids,  when  the  latter  contain  but  little  mort 
than  hal^the  quantity  of  tin  which  they  are  capable  of  dissolving. 


360  Philosophy  of  Permanent  Colours, 

ing  it  boil,  and  continue  the  operation  as  usual  until  the 
colour  be  duly  raised,  and  the  dyeing  liquor  exhausted, 
which  will  be  the  case  in  about  fifteen  or  twenty  minutes; 
alter  which  the  cloth  may  be  taken  out  and  rinced  as 
usual.  In  this  w^ay  the  time,  labour,  and  fuel,  necessary 
for  filling  and  heating  the  dyeing  vessel  a  second  time, 
will  be  saved;  the  operation  finished  much  more  speedily 
than  in  the  common  way;  and  there  w  ill  be  a  saving  of  all 
the  tartar,  as  well  as  of  two-thirds  of  the  cost  of  spirit,  or 
nitro  muriatic  solution  of  tin,  which  for  dyeing  lOOlbs.  of 
wool,  commonly  amounts  to  10^.;  whereas,  eight  pounds 
of  the  murio- sulphuric  solution  will  only  cost  about  3s. 
There  will  be,  moreover,  a  saving  of  at  least  one-fourth 
of  the  cochineal  usually  employed,  (which  is  generally 
computed  at  the  rate  of  one  ounce  for  every  pound  of 
cloth,)  and  the  colour  produced  will  certainly  not  prove 
inferior  in  any  respect  to  that  dyed  with  much  more  ex- 
pense and  trouble  in  the  ordinary  way.  When  a  rose- 
colour  is  wanted,  it  may  be  readily  and  cheaply  dyed  in 
this  way,  only  omitting  the  quercitron  bark,  instead  of 
the  complex  method  now  practised  of  first  producing  a 
scarlet,  and  then  changing  it  to  a  rose  by  the  volatile  al- 
kali contaiiiCd  in  stale  urine,  set  free  or  decomposed  by- 
potash  or  by  lime:  and,  even  if  any  one  should  still  un- 
wisely  choose  to  continue  the  practice  of  dyeing  scarlet 
without  quercitron  bark,  he  need  only  employ  the  usual 
proportions  of  tartar  and  cochineal,  witli  a  suitable  quan- 
tity  of  the  murio- sulphate  of  tin,  which,  whilst  it  costs 
so  much  less,  will  be  more  effectual  than  the  dyers' 
spirit.* 

*  The  murio-sulphate  of  tin  here  recommended,  is  now  employed 
by  the  dyers  in  many  parts  of  England,  particularly  in  Yorkshire  and 
Lancashire,  though  many  of  them  do  not  know  how,  or  with  what 
acids  it  is  prepared.  A  considerable  distiller  of  aqua- fortis,  and  of  mu- 
riatic acid,  who  also  prepares  solutions  of  tin  in  large  quantities,  in- 


Philosophy  of  Permanent  Colours,  361 

Several  hundreds  of  experiments  warrant  my  assertion, 
that  at  least  a  fourth  part  of  the  cochineal  generally  em- 
ployed in  dyeing  scarlet,  may  be  saved  by  obtaining  so 
much  yellow  as  is  necessary  to  compose  this  colour  from 
the  quercitron  bark;  and  indeed  nothing  can  be  more 
self-evident,  than  that  such  an  effect,  ceteris  paribus, 
ought  necessarily  to  result  from  this  combination  of  dif- 
ferent colouring  matters,  suited  to  produce  the  compound 
colour  in  qnestion.  Let  it  be  recollected  that  the  cochi- 
neal crimson,  though  capable  of  being  changed  by  the 
acid  of  tartar  towards  the  yellow  hue  on  one  hand,  is  also 
capable  by  different  means,  of  being  changed  towards  a 
blue  on  the  other,  and  of  thereby  producing  a  purple 
without  indigo  or  any  other  blue  colouring  matter:  yet  I 
am  confident  that  nobody  would  believe  a  pound  of  co- 
chineal so  employed,  capable  alone  of  dyeing  as  much 
cloth,  of  any  particular  shade  of  purple,  as  might  be  dyed 
with  it,  if  the  whole  of  its  colouring  matter  were  employ- 
ed solely  in  furnishing  the  crimson  part  of  the  purple, 
whilst  the  other  (blue)  part  thereof  was  obtained  from 
indigo.  To  say  that  a  pound  of  cochineal  alone  could 
produce  as  much  effect  or  colour  as  a  pound  of  cochineal 
and  a  pound  of  indigo  together,  would  be  an  improbabi- 
lity much  too  obvious  and  palpable  for  human  belief;  and 
there  certainly  would  be  a  similar  improbability  in  al- 

forms  me  that  he  is  in  the  practice  of  selling  this  preparation  of 
that  metal,  under  another  denomination,  and  that  it  is  chiefly  em- 
ployed to  dye  the  most  vivid  and  beautiful  yellows  from  querci- 
tron bark.  It  has  also  been  of  late  used  to  dye  scarlet  with  a  prepa- 
ration called  lac  lake,  made  (in  the  East  Indies)  from  the  stick  laC, 
to  be  noticed  in  my  next  chapter. 

Mr.  Hawker  (near  Stroud,  in  Gloucestershire,)  lately  mentioned 
at  p.  337,  told  me,  in  1795,  soon  after  the  publication  of  my  first 
edition,  that  he  had  prepared  the  murio-sulphate  of  tin,  according  to 
my  direction,  and  found  it  answer  the  purpose  for  which  it  had  been 
recommended  by  me. 

Vol.  I.  2  Z 


.362  Philosophy  of  Permanent  Colours. 

leging,  that  a  pound  of  cochineal,  eraployed  in  giving 
another  compound  colour  (scarlet),  could  alone  produce 
as  much  effect  as  a  pound  of  cochineal  and  a  pound  of 
qiiercitron  bark,  when  the  colour  of  this  last  wag  employ- 
ed only  in  furnishing  one  of  the  component  parts  of  the 
scarlet,  for  which  a  considerable  portion  of  the  colouring 
matter  of  the  cochineal  must  otherwise  have  been  ex- 
pended, which  certainly  happens  in  the  new  mode  of  dye- 
ing scarlet,  because  the  colour  produced  with  an  addi- 
tion of  the  quercitron  yellow  inclines  no  more  towards  a 
yellow,  than  the  scarlet  produced  by  yellowing  a  part  of 
the  cochineal  colour  in  the  usual  method  with  tartar.  I 
retain,  therefore,  at  this  moment,  as  much  confidence  as 
I  ever  had  in  the  reality  and  importance  of  my  proposed 
improvements  in  this  respect.* 

The  scarlet  composed  of  cochineal  crimson  and  quer- 
citron yellow,  is  moreover  attended  with  this  advantage, 
that  it  may  be  dyed  upon  wool  and  woollen  yarn,  with- 
out any  danger  of  its  being  changed  to  a  rose  or  crimson, 
by  the  process  of  fulling,  as  always  happens  to  scarlet 
dyed  by  the  usual  means.  This  last  being  in  fact  nothing 
but  a  crimson  or  rose  colour,  yellowed  by  some  specific 
or  particular  action  of  the  acid  of  tartar,  is  liable  to  be 
made  crimson  again  by  the  application  of  many  chemical 

*  Of  the  benefit  which  I  formerly  expected  to  obtain  by  employ- 
ing potash  or  soda  to  extract  a  part  of  the  cochineal  colour,  which 
water  alone  did  not  appear  capable  of  extracting,  it  must  be  re- 
marked, that  I  have  some  time  since  convinced  myself  of  its  being 
an  illusion;  for,  by  repeated  trials,  I  have  found  that  the  solid  parts 
of  powdered  cochineal  remaining  after  it  has  been  boiled  with  the 
solution  of  tin  and  tartar,  as  in  the  common  dyeing  process,  yield 
no  colour  worthy  of  notice,  upon  the  application  of  potash;  the  so- 
lution of  tin  and  tartaric  acid,  enabling  the  water  to  extract  the  co- 
lour sufficiently;  so  that  in  truth  there  is  no  such  waste  of  cochi- 
neal colour  as  1  had  supposed,  in  the  usual  way  of  employing  that 
drug. 


Philosophy  of  Permanent  Colours.  363 

agents,  (which  readily  overcome  the  changeable  yellow 
produced  by  the  tartar,)  an  particularly  by  calcareous 
earths,  soap,  alkaline  salts,  &.c.  But  where  the  cochineal 
colouring  matter  is  applied  and  fixed  merely  as  a  crimson 
or  rose  colour,  and  is  rendered  scarlet  by  superadding  a 
very  permanent  quercitron  yellow,  capable  of  resisting  the 
strongest  acids  and  alkalies,  (which  it  does  when  dyed 
with  solutions  of  tin,)  no  such  change  can  take  place, 
because  the  cochineal  colour  having  never  ceased  to  be 
crimson,  cannot  be  rendered  more  so,  and  therefore  can- 
not suffer  by  those  impressions  or  applications  which 
frequently  change  or  spot  scarlets  dyed  according  to  the 
present  practice.* 

There  is  also  a  singular  property  attending  the  com- 
pound scarlet  dyed  with  cochineal  and  quercitron  bark; 
which  is,  that  if  it  be  compared  with  another  piece  of 
scarlet  dyed  in  the  usual  way,  and  both  appear  by  day- 
light exactly  of  the  same  shade,  the  former,  if  they  be 
afterwards  compared  by  candle-light,  will  appear  to  be  at 
least  several  shades  higher  and  fuller  than  the  latter;  a 
circumstance  of  some  importance,  when  it  is  considered 
how  much  this  and  other  gay  colours  are  generally  worn 
and  exhibited  by  candle-light  during  a  considerable  part 
of  the  year. 

To  illustrate  more  clearly  the  effects  of  the  murio- sul- 
phuric solution  of  tin  with  cochineal  in  dyeing,  I  shall 
state  a  very  few  of  my  numerous  experiments  therewith; 

*  MM.  Thcnard  and  Roard,  in  their  *'  Memoire  sur  les  mordants 
employes  dans  la  teinture,"  observe,  that  ever  since  the  discovery 
of  scarlet,  its  liability  to  become  crimson  has  been  complained  of, 
loithout  any  attempt  to  ascertain  and  obviate  the  cause  of  that  defect. 
In  making  the  latter  part  of  this  observation,  they  must  surely  have 
forgotten,  or  never  have  been  made  acquainted  with  this  part  of 
my  publication,  which  had  preceded  their  memoir  sixteen  yearso 


364  Philosophy  of  Permanent  Colours, 

observing,  however,  that  they  were  all  several  times  re- 
peated, and  always  with  similar  effects. 

1st.  I  boiled  one  hundred  parts  of  woollen  cloth  in 
water,  with  eight  parts  of  the  murio- sulphuric  solution  of 
tin,  during  the  space  of  ten  or  fifteen  minutes;  I  then 
added  to  the  same  water  four  parts  of  cochineal,  and  two 
parts  and  a  half  of  quercitron  bark  in  powder,  and  boiled 
the  cloth  fifteen  or  twenty  minutes  longer;  at  the  end  of 
which  it  had  nearly  imbibed  all  the  colour  of  the  dyeing 
liquor,  and  received  a  very  good,  even,  and  bright  scar- 
let. Similar  cloth  dyed  of  that  colour  at  the  same  time 
in  the  usual  way,  and  with  a  fourth  part  more  of  cochi- 
neal, was  found  upon  comparison  to  have  somewhat  less 
body  than  the  former;  the  effect  of  the  quercitron  bark 
in  the  first  case  having  been  more  than  equal  to  the  ad- 
ditional portion  of  cochineal  employed  in  the  latter,  and 
made  yellow  by  the  action  of  tartar. 

2d.  To  see  whether  the  tartrite  of  tin  would,  besides 
yellowing  the  cochineal  crimson,  contribute  to  raise  and 
exalt  its  colour  more  than  the  murio-sulphate  of  that 
metal,  I  boiled  one  hundred  parts  of  cloth  with  eight 
parts  of  the  murio-sulphuric  solution,  and  six  parts  of  tar- 
tar, for  the  space  of  one  hour;  I  then  dyed  the  cloth,  un- 
rinced,  in  clean  water,  with  four  parts  of  cochineal,  and 
two  parts  and  a  half  of  quercitron  bark,  which  produced 
a  bright  aurora  colour,  because  a  double  portion  of  yel- 
low had  been  here  produced,  first  by  the  quercitron  bark, 
and  then  by  the  action  of  tartar  upon  the  cochineal  colour- 
ing matter.  To  bring  back  this  aurora  to  the  scarlet  co- 
lour, by  taking  away  or  changing  the  yellow  produced 
by  the  tartar,  I  divided  the  cloth  whilst  unrinced  into 
three  equal  parts,  and  boiled  one  of  them  a  few  minutes 
in  water,  slightly  impregnated  with  potash;  another  in 
water  with  a  little  ammonia;  and  the  third  in  water  con- 
taining a  very  little  powdered  chalk,  by  which  all  the 


Philosophy  of  Permanent  Colours,  365 

pieces  became  scarlet;  but  the  two  last  appeared  some- 
what brighter  than  the  first,  the  ammonia  and  chalk  hav- 
ing  each  rosed  the  cochineal  colour  rather  more  advanta- 
geously than  the  potash.  The  best  of  these,  however,  by 
comparison,  did  not  seem  preferable  to  the  compound 
scarlet  dyed  without  tartar,  as  in  the  preceding  experi- 
ment; consequently  this  did  not  seem  to  exalt  the  cochi- 
neal colour  more  than  the  murio-sulphate  of  tin;  had  it 
done  so,  the  use  of  it  in  this  way  would  have  been  easy, 
without  relinquishing  the  advantages  of  the  quercitron 
yellow. 

3d.  I  boiled  one  hundred  parts  of  woollen  cloth  with 
eight  parts  of  the  murio-sulphuric  solution  of  tin,  for 
about  ten  minutes,  then  added  four  parts  of  cochineal  in 
powder,  which  by  ten  or  fifteen  minutes  more  of  boiling, 
produced  a  fine  crimson.  This  I  divided  into  two  equal 
parts,  one  of  which  I  yellowed  or  made  scarlet  by  boiling 
it  for  fifteen  minutes  with  a  tenth  of  its  weight  of  tartar 
in  clean  water;  and  the  other,  by  boiling  it  with  a  fortieth 
of  its  weight  of  quercitron  bark,  and  the  same  weight  of 
murio-sulphuric  solution  of  tin;  so  that  in  this  last  case 
there  was  an  addition  of  yellow  colouring  matter  from 
the  bark,  whilst  in  the  former  no  such  addition  took 
place,  the  yellow  necessary  for  producing  the  scarlet  hav- 
ing been  wholly  gained  by  a  change  and  diminution  of 
the  cochineal  crimson  or  rose  colour;  and  the  two  pieces 
being  compared  with  each  other,  that  which  had  been 
rendered  scarlet  by  an  addition  of  quercitron  yellow,  was, 
as  might  have  been  expected,  several  shades  fuller  than 
the  other. 

4th.  I  dyed  one  hundred  parts  of  woollen  cloth  scarlet, 
by  boiling  it  first  in  water  with  eight  parts  of  murio-sul- 
phate of  tin,  and  twelve  parts  of  tartar,  for  ten  minutes, 
and  then  adding  five  parts  of  cochineal,  and  continuing 
the  boiling  for  fifteen  minutes.  This  scarlet  cloth  I  divi- 


366  Philosophy  of  Permanent  Colou/s. 

ded  equally,  and  made  one  part  crimson,  by  boiling  it 
with  a  iitde  ammonia  in  clean  water;  after  which  I  again 
rendered  it  sc  arlet,  by  boiling  it  in  clean  water  with  a  for- 
tieth of  its  weight  of  quercitron  bark,  and  the  same  weight 
of  murio- sulphate  of  tin;  and  this  last,  being  compared 
with  the  other  half,  to  which  no  quercitron  yellow  had 
been  applied,  was  found  to  possess  the  most  colour,  as 
might  have  been  expected.  A  piece  of  the  cloth,  which 
had  been  dyed  scarlet  by  cochineal  and  quercitron  bark, 
as  in  the  first  experiment,  being  at  the  same  time  boiled 
in  the  same  water  with  ammonia,  did  not  become  crim- 
son, like  that  dyed  scarlet  without  the  bark. 

In  this  way  of  compounding  a  scarlet  from  cochineal 
and  quercitron  bark,  the  dyer  will  at  all  times  be  able, 
with  the  utmost  certainty,  to  produce  every  possible 
shade  between  the  crimson  and  yellow  colours,  by  only 
increasing  or  diminishing  the  proportion  of  bark.  It  has, 
indeed,  been  usual  at  times  when  scarlets,  approaching 
nearly  to  the  aurora  colour,  were  in  fashion,  to  superadd 
a  fugitive  yellow  either  from  turmeric,  or  from  what  is 
called  young  fustic  (rhus  cotinus;)  but  this  was  only 
when  the  cochineal  colour  had  been  previously  yellowed 
as  much  as  possible  by  the  use  of  tartar,  as  in  the  com- 
mon way  of  dyeing  scarlet;  and  therefore  that  practice 
ought  not  to  be  confounded  with  my  improvement,  which 
has  for  its  object  to  preclude  the  loss  of  any  part  of  the 
cochineal  rose  or  crimson,  by  its  conversion  towards  a 
yellow  colour,  which  may  be  so  much  more  cheaply  ob- 
tained from  the  quercitron  bark. 

By  sufficient  trials,  I  have  satisfied  myself  that  the  co- 
chineal colours,  dyed  with  the  murio-sulphuric  solution  of 
tin,  are  in  every  respect  at  least  as  durable  as  any  which 
can  be  dyed  with  an}  other  preparation  of  that  metal;  and 
they  even  seem  to  withstand  the  action  of  boiling  soap- 
suds  somewhat  longer,  and  therefore   I  cannot  avoid 


Philosophy  of  Permanent  Colours.  367 

eartiestly  recommending  its  use  for  dyeing  rose  and 
other  cochineal  colours,  as  well  as  for  compounding  a 
scarlet  with  the  quercitron  bark. 

Having  ascertained  about  the  time  of  the  publication 
of  my  first  edition  of  this  volume,  that  the  red  colour  af- 
forded by  madder,  might  be  greatly  exalted  and  bright- 
ened by  employing  it  with  the  murio-sulphate  of  tin,  and 
indeed,  with  the  nitro- muriate  and  the  muriate  of  that 
metal,  (instead  of  alum,)  and  that  the  lively  yellowish  red 
so  produced,  was  extremely  durable,  it  occurred  to  me, 
that  there  might  be  an  advantage  at  least  for  ordinary 
scarlets,  in  substituting  the  madder  for  the  quercitron 
bark,  to  compose  a  scarlet  with  cochineal,  on  the  princi- 
ple before  explained;  because  the  former  might  be  made 
not  only  to  supply  the  yellow  part  of  the  scarlet,  but  also 
a  portion  of  red,  in  aid  of  the  cochineal  colour,  without 
perceptibly  detracting  from  the  vivacity  of  the  latter; — 
with  this  expectation,  I  soon  after  made  a  great  number 
of  experiments,  which  fully  answered  my  expectation, 
and  proved  by  their  general  -results,  that  cloth  prepared 
by  boiling  the  usual  time  with  murio-sulphate  of  tin,  (the 
acids  not  being  saturated  by  the  metal,)  and  without  tartar, 
and  afterwards  dyed  with  cochineal  and  the  finest  Zealand 
madder,  in  the  proportion  of  from  two  to  three  or  even 
four  pounds  of  the  latter,  with  one  of  the  former,  might 
be  made  to  acquire  a  good  scarlet,  with  a  saving  of  one 
fourth  or  one  fifth  of  the  cochineal,  which  would  have 
been  necessary  to  produce  it  alone.  When  more  of  mad- 
der than  the  proportion  just  mentioned  was  employed, 
the  colour,  if  contrasted  with  a  very  fine  scarlet,  appear- 
ed to  incline  towards  a  yellowish  brown  tint,  though,  to 
common  eyes,  this  would  be  hardly  perceived  without  such 
contrast.  It  must,  however,  be  admitted,  that  for  scarlets 
which  are  intended  to  excel  and  vie  with  those  of  Mr. 
Nash  or  his  successor,  it  would  be  advisable  to  employ 


368  Philosophy  of  Permanent  Colours. 

cochineal  alone,  or  with  the  quercitron  yellow  instead  of 
the  madder  red,  cheapness  being  for  them  of  less  impor- 
tance than  beauty  of  colour.  But  for  ordinary  scarlets,  I 
am  convinced  it  may  be  employed  as  just  mentioned, 
without  any  perceptible  degradation  of  the  colour,  and 
with  a  considerable  diminution  of  expense. 

I  have  thus  freely  given  the  results  of  a  multitude  of 
experiments,  on  which  I  have  expended  money,  with 
much  more  of  time  and  meditation;  and  though  some 
years  may  elapse  before  the  truth  and  importance  of  what 
I  here  offer  are  fully  recognized,  I  am  confident  this  will 
happen  sooner  or  later;  and  by  putting  it  into  every  one's 
power  to  bring  my  ideas  to  the  test  of  experience,  I  shall 
have  at  least  done  my  duty.* 

I  had  not  particularly  directed  my  attention  to  the 
dyeing  of  scarlet,  until  the  year  1786,  when  no  person, 
so  far  as  I  have  been  able  to  discover,  had  ever  attempted 
to  ascertain  the  effects  of  any  solution  or  preparation  of 
tin,  excepting  that  with  the  nitric  or  nitro- muriatic  acids 
upon  the  colouring  matter  of  cochineal;  and  I  shall  there- 
fore state  the  results  of  numerous  experiments  which  I 
have  since  made,  with  that  metal,  differently  combined, 
and  at  various  degrees  of  oxidation,  omitting  all  detailsi 
respecting  proportions,  and  modes  of  conducting  the  dye- 
ing operations,  which  are  to  be  understood  as  having 
been  conformable  to  the  common  practice  where  nothing 
is  mentioned  to  the  contrary. 

Woollen  cloth,  dyed  with  cochineal  and  pure  nitrate  of 
tin  recently  prepared,  produced  a  fine  crimson,  and  this, 

*  A  portion  of  yellow  colouring  matter,  obtained  either  from  the 
quercitron  bark  or  the  rhus  cotinus,  is  now  (1812,)  very  generally 
employed  in  this  country  with  cochineal,  for  dyeing  scarlet;  not  in- 
deed, without  tartar,  but  with  a  smaller  quantity  than  that  which  is 
employed  in  other  countries,  and\vhich  was  formerly  employed  in 
this. 


Philo&ophy  of  Permanent  Colours,  369 

boiled  in  the  same  liquor  with  tartar,  was  changed  to  a 
good  scarlet.  A  similar,  but  rather  better  effect  was  pro- 
duced by  tin  dissolved  immediately  in  a  mixture  of  aqua- 
fortis and  tartar.  The  scarlet  given  by  this  tartaro-nitrate 
of  tin  appeared  highly  beautiful. 

Tin  put  into  aqua-fortis,  with  a  considerable  portion 
of  refined  sugar,  afforded  a  very  thick  adhesive  solution, 
which  assumed  a  blackish  brown  colour,  like  that  of 
burnt  sugar,  and  being  tried  as  a  mordant  in  dyeing,  it 
was  found  incapable  of  fixing  the  cochineal  or  any  other 
colours.  The  tin  in  this  state  did  not  seem  fitted  to  com- 
bine with  the  fibres  of  the  cloth,  and  the  sugar  had  mani- 
festly suffered  a  kind  of  combustion,  having  probably  in 
this  case  produced,  upon  the  tin,  as  it  does  with  indigo, 
(see  p.  161,)  a  deoxygenating  effect.  Spirit  of  wine,  put 
with  tin  into  aqua-fortis,  also  rendered  the  solution  unfit 
to  serve  as  a  mordant,  and,  as  I  conclude,  by  a  similar 
deoxygenation. 

Tin,  granulated  and  calcined  with  an  equal  quantity  of 
saltpetre,  in  a  red-hot  crucible,  being  thrown  into  water, 
afforded  a  milky  solution,  tasting  very  sensibly  of  the  al- 
kaline part  of  the  saltpetre,  and  evidently  suspending  a 
considerable  portion  of  the  metallic  calx.  Cloth  boiled  in 
water  with  some  of  this  solution,  then  rinced,  and  dyed 
with  cochineal,  took  a  crimson,  inclining  to  the  purple; 
and  this,  boiled  in  the  same  liquor  with  tartar,  was  chang- 
ed to  scarlet. 

Having  poured  two  pounds  of  aqua-fortis,  with  an 
equal  weight  of  water,  upon  a  large  quantity  of  granula- 
ted tin,  and  left  them  together  during  the  three  summer 
months  of  1790, 1  afterwards  found  near  a  pound  of  the 
calx  of  tin  collected  in  solid  lumps  at  the  bottom  of  the 
glass  vessel.  This  being  separated  and  dried,  some  of  it 
was  finely  powdered  and  thoroughly  washed;  and  being 
put  with  an  equal  weight  of  cochineal  into  water,  I  boiled 

Vol.  I.  3  A 


370  Philosophy  of  Permanent  Colours. 

cloth  therein,  which  took  a  full  equal  crimson,  somewhat 
deficient  in  brightness.*  Tartar  being  added  to  the  liquor, 
and  the  cloth  farther  boiled  therein,  it  acquired  a  good 
scarlet.  Lemon  juice  used,  instead  of  tartar,  produced  the 
like  effect.  By  substituting  caustic  volatile  alkali  for  tar- 
tar and  lemon  juice,  a  crimson,  greatly  inclining  to  pur- 
ple, was  produced.  The  oxide  of  tin,  therefore,  does  not 
act  in  all  cases  merely  as  such,  but  its  effects  often  depend 
on  triple,  quadruple,  and  sometimes  even  more  complex 
combinations,  in  which  different  saline  and  other  parts  of 
the  compound  remain  permanently  united,  at  least  where 
the  shades  of  colour  depending  on  them  are  found  per- 
manent. It  is  thus  that  sea- salt,  and  other  purely  saline 
matters,  which,  having  no  earthy  or  metallic  basis,  can- 
not become  the  basis  of  any  adjective  colour,  produce 
lasting  effects  in  modifying  and  varying  the  shades  of  dif- 
ferent colours.! 

It  must,  however,  be  observed,  that  though  the  calx 
of  tin,  just  mentioned,  was,  after  being  thoroughly  wash- 

*  The  calx  or  oxide  of  tin  employed  for  this  experiment,  was 
some  of  that  which  is  mentioned  at  pages  159  and  160,  as  having 
efficaciously  c/coxygenated  indigo:  consequently  it  was  far  from  be- 
ing in  the  state  of  a  peroxide,  or  at  the  maximum  of  oxygenation; 
in  which  state  I  consider  tin  as  being  incapable  of  producing  with 
cochineal  any  thing  more  red  or  elevated  than  an  orange,  or  a 
salmon  colour,  at  the  most. 

t  Hellot  describes,  at  p.  234,  a  "  Cramoisi  de  Languedoc"  which 
was  dyed  with  cochineal  upon  cloth,  prepared  as  for  the  scarlet 
dye,  excepting,  that  instead  of  tartar,  sea-salt  was  added  to  the  so- 
lution of  tin;  which  addition  caused  the  colour  to  incline  towards 
the  purple  or  dark  crimson;  an  effect  which  all  the  mineral  acids 
seem  to  produce  with  cochineal,  when  neutralized  by  soda,  and 
more  especially  by  potash;  and  therefore,  in  making  the  common 
dyers*  spirit,  when  nitric  and  muriatic  acids,  perfectly  free  from  the 
sulphuric,  can  be  had,  it  would  be  better  to  employ  the  muriatic 
acid  instead  of  sea-salt,  especially  when  very  bright  scarlets  are 
wanted. 


Philosophy  of  Permanent  Colours.  371 

cd  and  dried,  capable  of  dyeing  a  crimson  on  woollens 
with  cochineal,  and  a  scarlet,  where  either  tartar,  lemon 
juice,  or  quercitron  bark  were  added,  it  would  not  per- 
manently  combine  with,  or  become  the  basis  of,  these 
colours  upon  cotton;  and  indeed,  on  woollen  it  was  only 
the  finer  particles  of  the  calx  which  really  combined  with 
the  colouring  matter  and  the  wool,  the  grosser  being  al- 
ways  distinctly  found  at  the  bottom  of  the  dyeing  vessel; 
and  when  I  attempted  to  impregnate  woollen  cloth  with 
this  oxide  of  tin  only  by  boiling  them  together,  I  always 
found,  on  rincing  the  cloth,  and  endeavouring  to  dye  it 
with  cochineal  in  a  different  vessel  or  bath,  that  the  oxide 
had  not  penetrated  or  united  with  the  wool,  so  as  to  af- 
ford a  basis  for  raising  and  fixing  the  colour,  it  being 
necessary  for  this  purpose,  that  both  the  oxide  and  the 
colouring  matter  should  be  mixed  together  in  the  dye- 
ing vessel,  and  exert  their  mutual  attractions  for  and  upon 
each  other,  before  they  could  be  properly  taken  up  by 
the  cloth;  and  this  was  done  better  after  they  had  been 
previously  mixed  and  left  together  for  several  hours. 

One  ounce  of  the  calx  of  tin  before  mentioned,  un- 
washed, being  dissolved  in  three  ounces  of  muriatic  acid, 
and  woollen  cloth  being  dyed  with  a  tenth  of  its  weight 
of  this  solution,  and  a  twentieth  of  cochineal,  it  took  but 
a  very  languid  colour.  The  oxide  of  tin,  (probably  from 
too  much  oxidation,)  being  immediately  decomposed  upon 
its  intermixture  with  water,  and  manifesting  very  little 
disposition  to  penetrate  or  combine  with  the  fibres  of  the 
wool;  so  that  after  long  boiling,  a  great  part  of  it,  and  of 
the  colouring  matter,  remained  suspended  in  the  dyeing 
liquor,  as  in  my  second  experiment  at  the  ^dye-house  of 
Messrs.  Goodwin  and  Co. 

Cochineal  with  a  solution  of  tin  by  muriatic  acid  only, 
dyed  a  beautiful  crimson  or  rose  colour;  and  with  a  solu- 


372  Philosophy  of  Permanent  Colours. 

tion  of  that  metal,  by  a  mixture  of  tartar  and  muriatic 
acid,  a  beautiful  scarlet. 

Cochineal,  with  tin  dissolved  by  a  mixture  of  muriatic 
and  pyroligneous  acid,  produced  a  dark  crimson;  and 
with  tin,  and  a  little  manganese  dissolved  in  muriatic  acid, 
it  produced  a  very  bluish  crimson. 

Cochineal,  with  tin  dissolved  by  muriatic  acid  and  bo- 
rax mixed,  dyed  a  very  good  crimson. 

Cochineal,  with  tin  calcined  by  the  long  continued  ac- 
tion of  sulphuric  acid,  dyed  a  salmon  colour;  and  with  a 
recent  solution  of  tin,  it  produced  a  reddish  salmon  co- 
lour, inclining  a  little  to  the  crimson.  A  like  colour  was 
produced  with  tin  dissolved  by  equal  parts  of  sulphuric 
and  nitric  acids  mixed. 

Oil  of  vitriol,  having  been  poured  upon  tartar  and  gra- 
nulated tin,  the  mixture  immediately  became  black,  by 
the  action  of  the  sulphuric  acid  upon  the  carbonic  basis, 
which,  with  hydrogene  and  ox}  gene,  are  the  constituents 
of  tartar.  Cloth,  dyed  with  a  tartaro-sulphuric  solution  of 
tin  thus  made,  and  cochineal,  took  an  aurora  colour. 

Tin  dissolved  by  the  pure  acid  of  tartar,  separated 
from  its  alkaline  basis,  (by  the  means  usually  employed 
for  that  purpose,)  dyed  with  cochineal  on  cloth  a  very 
lively  and  beautiful  scarlet,  inclining  a  little  to  the 
orange.  A  similar  colour  was  produced  by  water  satu- 
rated with  cream  of  tartar,  in  which  granulated  tin  had 
been  kept  six  weeks. 

Tin  may  be  readily  dissolved  by  pure  citric  acid,  and 
more  slowly  by  lemon  juice;  and  the  solution  newly  made, 
dyes^  with  cochineal,  a  most  beautiful  scarlet,  inclining, 
like  the  preceding,  a  little  to  the  aurora.  Indeed,  I  have 
repeatedly  found,  that  the  citric  acid  with  tin,  acts  at 
least  as  efficaciously  as  that  of  tartar  in  yellowing  the 
cochineal  crimson.  Nothing  can  exceed  the  beauty  of 
scarlet  dyed  with  the  citrate  of  tin,  and  if  it  were  not 


Philosophy  of  Permanent  Colours.  373 

too  costly^  this  solution  would  deserve  the  preference  of 
every  other  for  dyeing  scarlet. 

Granulated  tin,  dissolved  by  strong  vinegar,  acquired 
a  milky  appearance,  with  a  very  particular,  and  somewhat 
of  an  unpleasant  smell;  and  with  cochineal  it  dyed  cloth 
of  a  scarlet,  inclining  a  little  to  the  rose  colour. 

Tin  dissolved  by  the  pyroligneous  acid  produced  with 
cochineal  a  colour  between  the  scarlet  and  rose  colour. 

Phosphoric  acid  produced  a  permanently  transparent 
and  colourless  solution  of  tin,  which,  with  cochineal,  dyed 
a  bright  yellowish  scarlet. 

Tin,  dissolved  by  fluoric  acid,  produced  with  cochi- 
neal a  very  bright  scarlet. 

In  addition  to  this  account  of  experiments  made  pre- 
viously to  my  first  publication  on  this  subject,  I  will 
mention  a  few  of  those  which  I  have  since  made. 

Tin  having  been  dissolved  by  a  direct  mixture  of  pure 
nitric  and  muriatic  acids,  in  equal  proportions,  the  for- 
mer of  the  specific  gravity  of  1500,  and  the  latter  of 
1170,  this  solution,  with  cochineal  and  the  common  al- 
lowance of  tartar,  produced  a  very  bright  lively  scarlet. 

Tin,  having  been  dissolved  by  a  similar  mixture,  with 
an  addition  of  sulphuric  acid,  equal  to  one  fourth  of  the 
nitric,  and  the  solution  being  afterwards  employed  with 
cochineal  and  tartar,  as  in  the  last-mentioned  experiment, 
a  salmon  colour  only  was  produced. 

Tin,  being  dissolved  in  a  mixture  similar  to  that  last 
mentioned,  but  with  this  difference,  that  before  the  sul- 
phuric acid  was  added,  tartar,  amounting  to  three  times 
the  weight  of  the  sulphuric  acid,  had  been  mixed  with 
the  nitric  and  muriatic;  and  this  solution  being  employed 
with  cochineal,  and  a  little  more  tartar,  a  good  scarlet 
was  produced;  the  tartar  which  had  been  added  before 
the  sulphuric  acid  having,  by  its  alkaline  part,  neutraliz- 


374  PMlosophy  of  Permanent  Colours. 

ed  the  vitriolic  acid,  and  obviated  the  evil  produced  by 
the  latter,  in  the  preceding  experiment. 

Having  precipitated  the  oxide  of  tin,  (by  soda,)  from 
the  common  dyers'  spirit,  or  nitro- muriate  thereof,  and 
subjected  this  to  the  action  of  sulphuric  acid,  I  found  it 
incapable,  with  cochineal,  of  dyeing  any  colour  more 
elevated  than  the  orange. 

After  this  account  of  the  effects  of  'the  oxides  of  tin, 
in  various  states  and  combinations,  when  applied  with  co- 
chineal on  wool  or  woollen  cloths,  it  is,  I  think,  expe- 
dient for  me  to  add  a  few  other  observations  concerning 
those  particular  solutions  of  that  metal,  which  are  most 
frequently  employed  as  mordants  in  dyeing,  and  the 
means  by  which  they  may  be  most  advantageously  ob- 
tained and  employed. 

It  can  hardly  be  necessary  to  premise,  that  for  these 
solutions,  the  purest  tin  should  always  be  selected,  such 
as  that  of  Malacca;  next  to  which  is  that  of  Banca;  and 
after  it,  the  tin  of  Mexico  is  considered  as  most  pure. 
In  regard  to  the  tin  mines  of  Europe,  those  of  Cornwall 
afford  tin  of  the  greatest  purity;  and  after  these,  the 
tin  of  Bohemia  is  considered  as  preferable  to  that  of 
Saxony. 

The  most  frequent  adulterations  of  tin  are  produced 
by  intermixtures  of  arsenic,  lead,  copper,  and  iron.  The 
first  of  these  renders  tin  whiter  and  more  britde;  the 
others  give  it  sliades  of  grey,  which  are  dark,  when  either 
of  the  txvo  last  bears  a  considerable  proportion.  The 
means  of  detecting  these  adulterations  have  been  men- 
tioned by  most  of  the  systematic  chemical  writers.  The 
presence  of  either  iron  or  copper  in  tin,  may  be  readily 
ascertained  by  dissolving  a  little  of  it  in  pure  muriatic 
acid,  and  dropping  the  solution  into  a  prussiate  of  lime, 
which  will  afford  a  precipitate  more  or  less  blue^  if  the 


Philosophy  of  Permanent  Colours.  375 

tin  contains  iron;  and  if  it  contains  copper,  a  reddish 
bronze  precipitate. 

When  pure  colourless  nitric  and  muriatic  acids  are 
mixed  in  quantities  not  very  disproportionable,  the  former 
of  these  acids  will  be  partially  decomposed,  with  an  exha- 
lation of  oxymuriatic  acid,  and  a  production  of  nitrous 
gas;  but  this  last  will  remain  for  some  time  dissolved  by 
the  mixed  acids,  and  give  the  mixture  a  red  colour;  and 
if  granulated  tin  be  added  to  the  mixture,  it  will  soon 
destroy  ^this  red  colour,  by  expelling  the  nitrous  gas; 
and  will,  moreover,  cause  a  farther  decomposition  of  the 
nitric  acid,  by  combining  with  its  oxygene;  which  com- 
bination  renders  it  susceptible  of  a  more  speedy  dissolu- 
tion by  the  muriatic  part  of  the  compound. 

Dyers,  however,  do  not  commonly  produce  their  aqua- 
regia  by  a  simple  mixture  of  the  nitric  and  muriatic  acids, 
but  by  adding  to  single  aqua-fortis  a  portion  of  sea-sail; 
and  in  so  doing  they,  (without  knowing  it,)  obviate  the 
injury  which  the  small  proportion  of  sulphuric  acid  fre- 
quently contained,  either  in  aqua-fortis  or  in  muriatic 
acid,  would  produce,  if  allowed  to  act  upon  tin  in  con- 
junction with  nitric  acid;  as  I  have  found  by  numerous 
experiments.  But  in  this  way  of  producing  a  nitro-muri- 
atic  acid,  the  soda  contained  in  the  sea-salt,  by  combining 
with  the  sulphuric  acid,  and  forming  Glauber's  salt,  ren- 
ders the  latter  incapable  of  any  hurtful  action;  at  least,  if 
there  be  not  more  of  it  than  the  soda  of  the  seas-alt  can 
neutralize;  and  when  this  happens,  the  addition  of  a  little 
saltpetre,  which  Hellot  and  others  have  thought  benefi- 
cial, (without  assigning  any  reason  for  thinking  so,)  would 
render  this  excess  of  sulphuric  acid  harmless,  by  afford- 
ing potash  to  form  with  it  a  sulphate  thereof. 

By  modern  chemists,  the  solution  of  tin,  when  made 
by  nitro-muriatic  acid,  is  supposed  to  contain,  or  afford, 
only  a  inuriQte  of  that  metal;  it  being  assumed,  that  the 


376  Philosophy  of  Permanent  Colours. 

nitric  acid  suffers  a  complete  decomposition,  and  that  its 
oxygene  is  all,  either  expended  to  oxidate  the  metal,  or 
exhaled  with  the  nitrous  gas.  I  believe,  however,  that  the 
nitric  acid  is  never  completely  decomposed,  by  this  ope- 
rationj*  at  least  I  have  never  found  any  solution  of  tin 
made  by  nitro- muriatic  acid,  which  did  not  differ  con- 
siderably in  its  sensible  qualities,  and  also  in  its  effects, 
as  a  mordant,  with  cochineal,  &:c.  from  a  solution  of  that 
metal  by  pure  muriatic  acid.  I  attach  no  importance  to 
the  straw,  or  amber,  colour  of  the  solution  of  tin,  com- 
monly employed  by  the  dyers,  while  the  muriate  of  tin 
is  colourless;  because  the  colour  of  the  former  certainly 
results  from  the  neutral  salts  which  it  holds  dissolved; 
for,  when  the  solution  is  made  by  a  direct  mixture  of 
pure  nitric  and  muriatic  acids,  it  is  as  colourless  as  if  it 
had  been  made  by  muriatic  acid  only;  but  in  this  case,  it 
invariably  exhales,  and  for  a  long  time,  the  odour  of  ni- 
trous gas,  even  when  the  acids  were  mixed  in  equal  pro- 
portions; a  certain  proof,  that  the  nitric  acid  was  at  most 
but  partially  decomposed. 

*  The  proportion  of  either  sea-salt  or  muriate  of  ammonia,  em- 
ployed by  scarlet  dyers  in  making  their  ordinary  solution  of  tin,  is 
by  much  too  small  to  permit  us  to  believe  the  result  of  that  process 
to  be  merely  a  muriate.  Hellot,  who  prefers  a  muriate  of  ammonia 
to  sea-salt,  prescribes  as  the  best  proportion,  only  half  as  much  of  it 
in  weight,  as  of  the  metal  employed;  and  Dambournay  used  a  pro- 
portion smaller  than  Helloi's,  which,  however,  is,  I  believe,  that  of 
most  of  the  dyers,  whether  they  employ  sea-salt,  or  sal-ammoniac; 
and  certainly,  neither  of  these  could  afford  muriatic  acid  sufficient 
to  dissolve  twice  its  weight  of  tin,  as  it  must  do,  if  the  solution  so 
produced  were  merely  a  muriate  of  that  metal.  I  have  sometimes 
employed  a  solution  of  tin,  made  by  a  diluted,  but  very  pure  nitric 
acid,  with  an  addition  of  muriate  of  ammonia  amounting  tonoviore 
than  one-eighth  of  the  weight  of  metal  so  dissolved,  which  could 
have  contained  but  a  small  proportion  of  muriate  of  tin;  but  this  so- 
lution in  a  very  few  days  will  lose  its  transparency,  and  be  capable 
of  producing  only  orange  salmon  colours. 


Fhilosophy  of  Permanent  Colours.  377 

It  has,  moreover,  several  other  peculiarities,  particu- 
larly that  of  not  affording  crystals  by  evaporation,  like  the 
muriate  of  tin,  and  also  that  of  becoming  both  opake 
and  gelatinous  by  keeping,  which  does  not  happen  to 
the  muriatic  solution;  nor  does  it,  when  used  in  excess, 
injure  the  texture  of  wool,  so, much  as  an  equal  excess  of 
the  latter. 

One  cause  of  this  last  peculiarity,  or  difference,  may 
depend  upon  the  production  of  ammonia^  whenever  tin  is 
dissolved  by  nitro-muriatic  acid.  BerthoUet  obtained  sa- 
tisfactory evidence  of  the  reality  of  this  production,  even 
when  the  aqua-regia  was  made  by  a  direct  and  gradual 
mixture  of  the  pure  nitric  and  muriatic  acids;  and  he 
c^onsiders  it  as  being  a  fact,  which  may  enable  us  to  un- 
derstand, why  in  dyeing  there  is  less  difference  than  might 
be  expected,  between  the  effects  of  a  solution  of  tin,  made 
by  this  direct  and  simple  mixture  of  the  two  acids,  and 
those  of  a  solution  made  by  aqua-fortis  with  an  addition 
of  muriate  of  ammonia. 

Besides  this  production  of  ammonia,  M.  BerthoUet 
supposes,  that  another  occurs  in  the  dyeing  operation, 
whenever  the  heat  is  near  the  boiling  point;  and  that,  by 
this,  and  the  former  production  of  ammonia,  the  acidity 
of  the  solution  of  tin  is  greatly  diminished;  which,  as  he 
thinks,  will  enable  us  to  understand  why  the  cloth  is  not 
injured  by  the  common  process  for  dyeing  scarlet,  though 
the  nitric  acid  of  itself  would,  even  when  much  diluted, 
produce  hurtful  effects  upon  it;  and  he  also  considers  this 
as  explaining  the  cause  of  the  injury  which  the  cloth  suf- 
fered in  my  first  experiment  at  the  dye-house  of  Messrs. 
Goodwin  and  Piatt.* 


*  After  mentioning  the  neutralizing,  or  saturating  effect  of  the 
ammonia,  formed  and  acting,  as  has  been  just  stated,  M.  BerthoUet 
adds  "  on  trouve  encore  dans  cette  action  saturante  Texplication 

Vol.  I.  3  B 


378  Philosophy  of  Permanent  Colours, 

Having  ascertained,  as  is  mentioned  in  the  note  to  p. 
342,  that  a  muriate  of  tin,  containing  only  half  the  quan- 
tity of  that  metal,  which  the  acid  might  have  been  made 
to  dissolve,  had  operated  as  efficaciously  as  an  equal  quan- 
tity, containing  twice  as  much  tin,  and  in  some  respects 
with  a  better  effect,  in  the  dyeing  of  scarlet,  I  was  led  by 
this  and  other  facts  to  suspect,  that  a  much  smaller  pro- 
portion of  tin  than  that  which  the  dyers  commonly  dis- 
solve in  their  nitro- muriatic  acid,  would  produce  equally 
beneficial  effects.  And,  to  ascertain  the  truth  on  this 
point,  I  put  two  drachms  of  powdered  muriate  of  ammo- 
nia, into  three  ounces  of  strong  nitric  acid  of  the  specific 
gravity  of  nearly  1500;  and,  having  diluted  this  mixture 
by  adding  to  it  six  ounces  of  water,  I  made  it  gradually 
dissolve  fine  granulated  tin,  until  the  acid  was  completely 
saturated;  when  I  found  that  the  tin  so  dissolved  amount- 
ed  in  weight  to  a  little  more  than  half  the  weight  of  the 
nitric  acid.  On  the  same  day  I  made  another  solution, 
similar  in  every  respect  to  the  first,  excepting  only  that 
the  tin  dissolved  therein  weighed  only  half  as  much;  and 
with  these  solutions,  I  made  several  experiments,  the  two 
following  days,  which  were  afterwards  repeated,  and  in 
all  of  them  I  found,  that  the  solution  containing  only  half 
of  the  tin,  which  might  have  been  dissolved  therein,  pro- 
duced with  cochineal,  colours  which  at  least  were  in 
every  respect  as  good  as  those  resulting  from  an  equal 
quantity  of  the  saturated  solution;  and  after  I  had  ascer- 
tained by  several  trials  the  smallest  proportion  of  the  half 
saturated  solution  of  tin  which  was  necessary  to  produce 

d'une  observation  de  Bancroft,  II  vouloit  substituer  dans  la  tein- 
lure  de  Pecarlate,  le  muriate  d'etain,  au  nitro-muriate;  mais,  11  en 
falliit  line  plus  grande  proportion,  et  la  laine  se  trouvoit  fort  deterio- 
ree.  Dans  cette  operation,  il  ne  pouvoit  se  former  de  Tammoni- 
aque,  et  I'acide  muriatique,  qui  affaiblit  facilement  la  laine,  exer- 
9oit  sur  elle  toute  son  action."  Elemens,  &c.  torn.  i.  p.  385. 


Philosophy  of  Permanent  Colours.  379 

a  good  scarlet  upon  a  given  weight  of  broadcloth,  I  found, 
that  the  saturated  solution  would  only  produce  an  infe- 
rior colour,  when  (on  account  of  its  greater  proportion  of 
tin)  I  diminished  the  quantity  even  but  an  eighth  part.  I 
conclude,  therefore,  that  nearly  one  half  the  tin,  which 
the  scarlet  dyers  commonly  dissolve  with  aqua-fortis,  and 
a  little  sea- salt,  to  make  what  they  denominate  spirit^  is 
wastefully  employed;  a  fact  which,  considering  the  in- 
creased price  of  tin,  may,  by  proper  attention,  produce  a 
saving  of  very  considerable  importance.  It  appears  to 
me,  indeed,  from  a  variety  of  considerations,  that  a  pro- 
portion, and  not  a  small  one,  of  superfluous  or  unsatura- 
ted acid,  is  highly  useful  to  enable  the  basis,  or  oxide  of 
tin,  actually  employed,  to  produce  its  utmost  and  best 
eiFect,  by  conveying  it  more  copiously  and  thoroughly,  or 
with  greater  penetration^  into  the  substance  of  the  wool 
or  cloth.  For,  with  this  superfluous  acidity,  I  have  re- 
peatedly made  the  scarlet  dye  penetrate  completely  the 
innermost  parts  of  the  cloth,  without  any  of  the  means 
mentioned  in  a  note  at  p.  67,  as  having  been  employed 
by  Mr.  Nash^  and  his  successor,  for  this  purpose,  and 
without  any  other  means  excepting  the  use  of  a  super- 
fluous acidity;  and  I  think  one  of  the  benefits  resulting 
from  the  employment  of  tartar,  either  with  alum  or  with 
the  solutions  of  tin,  is  that  of  furnishing  a  portion  of  un- 
combined  acid,  in  addition  to  that  which  accompanies  the 
aluminous  or  metallic  basis;  which  basis,  being  thereby 
enabled  to  penetrate  wool  or  cloth  more  intimately,  after- 
wards attracts  the  colouring  matter  more  copiously  and 
thoroughly.  It  must  however  be  observed,  that  this  su- 
perfluity of  acids  may  be  too  great;  and  that  it  should 
never  be  employed  in  the  same  bath^  or  liquor^  which 
contains  the  cochineal,  but  always  in  the  previous  boiling; 
since  all  acids,  when  present  in  a  large  proportion,  weak- 
en or  render  latent  the  colour  of  that  insect. 


380  Philosophy  of  Permanent  Golours, 

In  regard  to  the  muriate  of  tin,  I  may  be  allowed  to 
premise,  that  the  muriatic  acid,  in  its  liquid  state,  is  ne- 
cessarily combined  with  water;  and  that  the  propor- 
tion of  the  latter,  in  which  the  acid  is  best  preserved,  and 
most  commonly  sold,  is  such  as  to  render  its  specific  gra- 
vity equal  to  1160,  or  at  most  1170;  and  that,  when  of 
the  latter  degrees  of  strength,  three  pounds  of  it  will  dis- 
solve nearly  one  pound  of  granulated  tin,  with  the  assist- 
ance of  a  sand-heat. 

When  purey  the  muriatic  acid  is  colourless;  though  it 
frequently  exhibits  a  light  straw  colour,  resulting,  as  is 
supposed,  from  a  small  portion  of  iron  dissolved  by  it: 
but  this  disappears  almost  instantaneously,  if  a  litde  tin 
be  dropped  into  the  acid. 

The  dissolution  of  tin  by  this  acid,  is  always  accom- 
panied by  a  copious  emission  of  bubbles,  which,  except- 
ing a  little  of  the  acid  escaping  at  the  same  time,  appear 
to  consist  of  hydrogene,  disengaged,  as  has  been  gene- 
rally believed,  in  consequence  of  a  decomposition  of  the 
water  previously  united  to  the  acid;  which  decomposition 
is  supposed  to  afford  oxygene  sufficient  to  oxidate  the 
metal,  as  far  as  is  necessary  to  render  it  soluble  by  the 
muriatic  acid.  Davy,  however,  in  reviving  the  doctrine  of 
Scheele,  endeavours  to  maintain,  that  the  muriatic  acid 
itself  contains  hydrogene,  which,  by  this  operation,  is  set 
free,  while  that,  which  he  supposes  to  be  its  elementary 
part,  and  which  he  denominates  chlorine,  dissolves  and 
combines  with  the  metal.  (See  Phil.  Trans,  for  1810.) 

Having  already,  in  the  introductory  part  of  this  vo- 
lume, stated  every  thing  which  I  mean  to  suggest,  on 
this  intricate  subject,  I  shall  proceed  to  observe,  that  how- 
ever the  emission  of  hydrogene  may  be  explained,  it  is 
attended  with  a  considerable  escape  of  muriatic  acid, 
which  carries  with  it  a  portion  of  the  metal  itself,  as  is 
manifested  by  the  smell.  Gay  Lussac  considers  himself 


Philosophy  of  Permanent  Colours,  381 

ais  having  ascertained  that  tin,  by  being  so  dissolved, 
combines  with  13,5  per  cent,  of  oxygene;  and  that,  by 
making  a  current  of  aqueous  vapour  pass  over  the  metal, 
in  a  red  heat,  a  white  oxide  may  be  produced,  similar  to 
that  which  is  formed  by  subjecting  tin  to  the  action  of 
concentrated  nitric  acid,  and  which,  according  to  his  ex- 
periments, consists  of  27,2  parts  of  oxygene  to  100  of 
tin.  (See  Ann.  deChimie,  torn.  80,  p.  169). 

Those  who  wish  to  dissolve  large  quantities  of  tin  by 
muriatic  acid,  will  find  it  advantageous  to  decompose  the 
dry  sea-salt,  by  employing  sulphuric  acid  in  the  propor- 
tion of  five  parts  of  the  latter  to  eight  of  the  former;  using 
the  precautions  which  have  been  prescribed,  by  chemical 
writers:  and,  by  collecting  the  muriatic  acid  as  set  free 
in  vapour,  and  conveying  it  immediately  into  large  re- 
ceivers, containing  granulated  tin  with  a  little  water,  to 
absorb  the  dry  acid  vapour,  the  heat  constantly  and  gra- 
dually evolved  by  that  absorption,  will,  (as  M.  Chaptal 
asserts,)  suifice  to  promote  a  solution  of  the  metal,  with- 
out any  expense  of  fuel.  (See  Chimie,  applique  aux 
Arts.  tom.  iv.  p.  182.)  In  this  way,  also,  the  loss  of  acid, 
and  of  tin,  by  evaporation,  may  be  in  a  great  degree  ob- 
viated; as  indeed  it  may  be  when  common  muriatic  acid 
is  employed  for  this  purpose,  if  the  solution  by  made  in 
tubulated  retorts.* 

*  Being  at  the  house  of  Mr.  Hawker,  at  Dudbridge,  near  Stroud^ 
in  Gloucestershire,  during  several  of  the  last  days  of  August,  1795, 
about  twelve  months  after  my  first  publication  on  this  subject,  that 
very  estimable  dyer  informed  me,  that  he  had  then  lately  begun  to 
employ  the  muriate  of  tin  for  dyeing  scarlet  with  good  effect,  and  a 
considerable  saving  of  expense  in  regard  to  the  mordant;  and  he 
also  showed  me  the  way  in  which  his  muriate  of  tin  was  prepared, 
which  was,  by  putting  large  portions  of  the  granulated  metal  into 
muriatic  acid  contained  in  capacious,  open  vessels,  and  leaving  it 
therein  several  weeks,  assisted  only  by  the  summer's  warmth:  a 
great  evaporation  and  waste  of  acid  unavoidably  occurred,  and  the 


382  Philosophy  of  Permanent  Colours. 

If  muriate  of  tin,  containing  one-fourth  of  its  weight  of 
the  metal,  be  sufficiently  evaporated,  it  will  afford  consi- 
derably more  than  half  its  weight  of  solid  transparent 
crystals,  which  are  the  heaviest  of  all  the  metallic  salts; 
but  the  evaporation  is  accompanied  with  a  pungent  disa- 
greeable odour,  produced  by  an  intimate  combination  of 
muriatic  acid  and  tin,  which  is  highly  volatile;  and,  conse- 
quently, the  bringing  such  a  solution  into  a  crystallized 
form,  must  be  attended  with  a  great  loss,  both  of  the  acid 
and  the  metal. 

Tin  when  first  dissolved  by  muriatic  acid,  is  supposed 
to  be  at  the  lowest  degree  of  oxidation,  but  if  the  atmo- 
sphere  be  allowed  free  access  to  the  solution,  it  will  con- 
stantly absorb  and  unite  with  an  increased  portion  of 
oxygene;  and  Pelletier  pretends,  that  in  proportion  as  it 
does  this,  and  becomes  most  oxidated^  it  also  becomes 
most  efficacious  and  useful  as  a  mordant  in  dyeing.*  But 
his  experiments  certainly  do  not  warrant  any  such  gene- 
ral inference;  and  the  numerous  trials  which  I  have  made 
of  this  metal  as  a  hasis^  (with  cochineal,  quercitron  bark, 
&c.,)  at  various,  and  probably  at  all  the  possible  degrees 
of  oxidation,!  have  abundantly  convinced  me,  that  the 

acid,  as  far  as  I  could  judge,  was  not  more  than  half  saturated; 
which  doubtless  was  an  advantage, 

*  See  Mem.  et  Observat.  de  Chimie,  torn.  i. 

1 1  am  aware  that  modern  chemists  are  disposed  to  consider  tin 
as  only  susceptible  of  two  stages  or  degrees  of  oxygenation;  the 
lowest  called  a  firotoxide^  in  which  the  metal  contains  about  13 
percent,  of  oxygene;  and  the  highest  called  peroxide,  in  which, 
according  to  some  estimations,  it  is  at  about  24  oxygene  to  76  of 
tin,  and,  according  to  others,  at  28  to  72.  I  believe,  however,  that  in 
my  experiments,  I  have  employed  this  metal  at  several  interme- 
diate stages  or  degrees  of  oxidation,  notwithstanding  all  that  has 
been  written,  and  particularly  by  Professor  Berzelius,  on  the  deter- 
minate firo/ioriions  in  which  the  inorganic  elements  of  nature  are 
supposed  to  unite. 


Philosophy  of  Permanent  Colours.  383 

oxide  of  tin  acts  most  powerfully  in  exalting  and  giving 
vivacity  to  colours,  when  it  is  but  little  oxidated,  and 
that  every  degree  of  oxygenation  beyond  a  certain  unas- 
certained number,  tends  to  reduce  or  diminish  the  high 
red  of  the  cochineal  dye,  and  at  the  same  time  to  make  it 
incline  to,  or  partake  of,  too  much  of  the  orange ^  so  as 
only  to  produce,  when  highly  oxidated,  what  I  have  de- 
nominated a  salmon  colour.  Such  is  invariably,  and  in  a 
remarkable  degree,  the  effect  of  tin,  when  it  has  been  sub- 
jected to  the  action  of  sulphuric  acid  alone,  or  in  con- 
junction with  the  nitric;  and  also  after  it  has  been  for 
some  time  rapidly  dissolved  by  pure  nitric  acid  but  little 
diluted;  and  it  can  hardly  be  necessary  for  me  to  add,  that 
in  all  these  cases  the  metal  will  have  obtained  a  higher 
degree  of  oxygenation.  Similar  effects,  though  in  smaller 
degrees,  have  been  found  to  result  from  a  variety  of  com- 
binations by  which  the  oxide  of  tin,  though  less  oxyge- 
nated than  in  the  former,  was  yet  too  much  so  to  pro- 
duce its  best  effects. 

In  stating  as  my  opinion,  that  tin  is  most  efficacious  in 
raising  and  giving  brightness  to  colours,  when  but  little 
oxidated,  I  purposely  avoided  the  word  least,  because  my 
experiments  do  not  warrant  me  to  say  that  colours  are 
not  as  much  exalted,  and  enlivened,  by  a  muriate  of  tin, 
to  which  a  little  nitric,  or  a  little  sulphuric  acid  has  been 
added,  (after  the  solution  was  made,)  as  by  the  muriate 
alone,  when  recently  made;  provided  that  only  one  of 
these  acids  be  added;  for  both  together  would,  as  has  al- 
ready been  observed,  render  the  tin  incapable  of  produ- 
cing, with  cochineal,  any  thing  more  elevated  than  a  sal- 
mon or  orange  colour.  But  in  attributing  such  effects  to 
variations  in  the  degrees  of  oxidation,  at  which  tin  is  em- 
ployed, I  desire  not  to  be  understood  as  believing,  that 
these  alone  operate,  in  producing  differences  in  the  shades 
of  cochineal  colours,  or  that  the  several  acids  employed 


3d4  Philosophy  of  Permanent  Colours, 

do  not  exercise  a  very  considerable  influence,  in  this^re- 
spect,  by  their  peculiar  properties,  independently  of  their 
effects  in  oxygenating  the  metal  itself. 

In  concluding  these  observations  concerning  the  muri- 
ate of  tin,  I  beg  leave  to  repeat,  what  has  been  already 
mentioned,  that  though  it  certainly  acts  more  strongly 
than  any  other  solution  of  that  metal,  in  weakening  the 
fibres  of  wool,  especially  when  the  acid  is  saturated  by 
the  metal,  it  may,  when  the  latter  is  dissolved  more  spa- 
ringly, be  employed  with  perfect  safety,  (and  a  consider- 
able saving  of  expense,)  and  more  especially  in  conjunc- 
tion with  the  usual  proportion  of  cream  of  tartar;  and  even 
with  a  considerable  proportion  of  sulphuric  acid,  which 
indisputably,  though  perhaps  unaccountably,  moderates 
this  hurtful  action  of  the  muriate  of  tin,^  as  indeed  every 
other  acid  seems  to  do. 

I  have  mentioned  with  approbation,  between  pages  286 

*  A  manufacturer  who  supplies  the  country  dyers  with  not  only 
the  muriate,  but  the  murio-sulphate  of  tin,  (recommended  at  p. 
358,)  assures  me,  that  to  produce  the  latter  he  first  prepares  the 
muriate  of  tin,  which  he  sells  of  two  sorts;  in  one  of  which  the  dis- 
solved metal  amounts  to  a  fourth,  and  in  the  other  to  a  fifth  part  of 
the  solution;  and  by  gradually  adding  tb  either  of  these  two-thirds 
of  its  weight  of  concentrated  oil  of  vitriol,  he  produces  a  murio- 
sulphate  of  tin,  in  which,  however,  the  acids  are  not  more  than  half 
saturated;  but,  notwithstanding  the  great  strength  of  these  acids, 
the  solution  has  not  been  even  suspected  of  producing  any  injury 
to  cloth  dyed  with  it;  and  the  preparer  of  it  asserts,  that  it  produces 
the  best  effects  after  being  kept  several  years.  No  length  of  time 
which  has  elapsed  since  it  was  first  made  and  recommended  by  me, 
seems  capable  of  diminishing  its  colourless  transparency,  which 
equals  that  of  the  clearest  spring-water;  a  circumstance  which 
seems  not  a  little  extraordinary,  when  we  consider  that  sulphuric 
acid  alone  is  speedily  decomposed  by  tin;  sulphur  being  distinctly 
produced,  and  the  tin  itself  converted  to  a  brownish  calx,  which 
subsides  in  a  wass  to  the  bottom  of  the  vessel,  in  which  the  decern* 
position  has  been  effected. 


Philosophy  of  Permanent  Colours*  385 

and  291,  the  results  of  several  experiments  made,  by 
MM.  Thenard  and  Roard,  to  ascertain  the  effects  pro- 
duced on  wool,  by  b  ling  it  with  the  usual  proportions 
of  alum  and  tartar,  and  also  with  the  usual  proportions 
of  the  latter,  and  of  the  nitro-muriate  of  tin,  as  employed 
for  the  dyeing  of  scarlet;  and  it  seems  ])roper  that  I 
should  here  notice  some  other  parts  of  their  *'  memoir e,^^ 
which  relate  more  immediately  to  the  production  of  this 
colour. 

•'  Scarlet,  (they  say,)  is  obtained  by  treating  wool  with 
determined  proportions  of  cochineal,  acidulated  tartrite  of 
potash,  and  a  highly  oxydized  solution  of  tin,'* ^  **  The 
operation  is  divided  into  two  parts;  the  first  taking  up  an 
hour  and  a  half,  and  the  second  half  an  hour:"  *' This 
division  (they  add)  is  necessary  to  produce  a  good  co- 
lour, which  would  be  weaker  and  more  yellow  if  all  the 
substances  were  mixed  in  the  first  operation  and  applied 
to  the  wool  for  two  hours,"  by  reason  of  the  acidity  of 
the  bath  or  dyeing  liquor.  **  We  obtain,"  say  they,  "  a 
contrary  eftect  when  the  mordants  only  are  employed  in 
the  first  operation,  and  the  cochineal  is  reserved  for  the 
second."  They,  however,  contradict  this  last  position, 
in  another  part  of  the  same  memoir,  by  asserting  that 
wool,  combined  with  the  mordants  in  question,  and  dyed 
afterwards  separately  with  cochineal  only,  will  never  be* 
come  scarlet;  because  this  colour,  as  they  allege,  can  only 
be  produced  by  a  cochineal  bath,  which  is  very  acid 
"  tres  acide,"  '*  et  qui  en  faisant  passer  aujaune,  le  ton 
de  la  cochenille,  donne  alors  tant  d'eclat  a  cette  cou- 
leur."*  But  the  effect  of  tartar,  which  principally  causes 
this  approach  to  yellow,  in  the  cochineal  colour,  may,  as 
I  have  found  by  scores  of  experiments,  be  very  well  pro- 
duced, together  with  that  of  the  solution  of  tin,  by  th^ 

*  See  Ann.  de  Chimie,  torn.  Jxxiv.  p.  39Q, 
Vol.  I.  3  C 


386  Philosophy  of  Permanent  Colours. 

first  boiling;  and  a  very  fine  scarlet  be  afterwards  dyed 
by  the  second  with  cochineal  alone,  taking  care  only, 
when  no  tartar  or  tin  is  intended  to  be  employed  in  the 
last  operation  with  the  cochineal,  that  a  full  proportion  of 
them  be  employed  in  the  first,  and  that  their  effects  be 
not  removed  or  diminished  by  rincing  the  cloth^  between 
the  first  and  second  boilings.  In  regard  to  the  inconve- 
nience  of  dyeing  scarlet  by  a  single  operation  or  boilings 
I  will  only  observe,  in  addition  to  what  I  have  stated  on 
that  subject  at  p.  337,  that  where  only  a  bare  sufficiency 
of  cochineal  is  employed,  with  a  full  proportion  of  the 
mordants,  and  especially  of  tartar,  the  colour,  though 
very  lively,  will  appear  rather  deficient  in  quantity,  or 
body,  because  the  cloth  will  not  completely  exhaust  the 
dyeing  liquor  of  its  colour,  when  the  acids  are  in  excess. 
This,  however,  Will  not  ultimately  be  attended  with  any 
waste  of  colour,  because  dyers,  by  a  succession  of  undyed 
pieces,  know  how  to  take  up,  and  fully  avail  themselves 
of  every  thing  left,  by  a  former  operation. 

In  regard  to  the  high  degree  of  oxidation  of  tin,  which 
these  gentlemen  consider  as  necessary  for  producing  a 
scarlet,  I  must  conclude,  that  they  have  been  misled  by 
the  opinion  of  Pelletier  on  this  subject,  or  that  they  have 
supposed  the  solutions  employed  by  them  to  be  much 
more  oxygenated  than  they  really  were.  Certainly  I  have 
produced,  as  I  believe,  more  than  one  hundred  times, 
scarlets  as  beautiful  as  can  be  any  where  found,  by  the 
recent y  and  little,  perhaps  least,  oxidated  muriate  of  tin, 
with  only  the  usual  proportions  of  tartar  and  cochineal; 
and  I  have  very  often  found  myself  unable  to  produce 
any  thing  better  than  an  orange  or  a  salmon  colour,  by 
solutions  of  tin,  which  certainly  were  highly  oxygenated. 
Indeed,  the  dyers  notoriously  and  universally  consider 
their  spirit,  or  nitro-muriatic  solution  of  tin,  as  being  unfit 
for  their  purpose,  when  it  loses  its  transparency;  an  effect 


Philosophy  of  Permanent  Colours.  387 

which  indicates,  and  results  from  a  greater  degree  of 
oxygenation  in  the  metal.* 

In  another  part  of  their  memoir,  these  gentlemen  are 
pleased  to  say,  that  though  the  process  for  dyeing  scarlet 
has  long  been  known,  no  person  has  made  any  theoretical 
researches,  concerning  the  phenomena  which  occur,  when 
the  solution  of  tin,  cream  of  tartar,  and  cochineal,  are 
made  to  act  upon,  or  with  each  other,  "  dans  le  traitement 
de  la  dissolution  d'etain  avec  la  creme  de  tartre  et  la  co- 
chenille;"  adding,  that  I,  who  (as  they  observe)  have  oc- 
cupied myself  with  great  success  in  dyeing,  have  indeed 
endeavoured  to  explain  what  occurs  in  the  formation  of 
the  scarlet  colour;  but  that  as  my  opinion  does  not  seem 
to  them  to  have  been  founded  upon  any  experiment ^  they 
are  intitled,  notwithstanding  that  opinion,  to  consider  the 
question  as  being  no  more  decided,  than  it  was  before  the 
publication  of  my  work.f  As  these  gentlemen  distinctly 
assert,  in  this  their  memoir,  that  the  production  of  a  scar- 

*  I  have  said,  at  p.  376,  that  the  straw  or  amber  colour  of  the  solu- 
tion of  tin,  commonly  employed  by  dyers,  appeared  to  result  from 
the  neutral  salts  which  it  holds  in  solution.  I  have,  however,  since 
discovered  that  I  was  then  misled  by  an  experiment  which  ought 
to  have  been  differently  explained,  and  that  thia  colour  may  be 
instantly  either  produced,  or  increased,  by  adding  a  very  little  mu- 
riate of  tin  to  the  nitro-muriate  of  that  metal;  the  former,  by  being 
thus  added,  producing  a  decomposition  of  the  nitric  acid  in  the  lat- 
ter, and  a  disengagement  of  reddish  nitrous  gas,  which  occasions 
the  colour,  and  affords  an  additional  proof  of  my  assertion,  at  p. 
376,  that  the  nitric  acid  is  never  completely  decomposed,  in  the 
dyers*  spirit,  or  nitro-muriate  of  tin. 

t  '*  Le  Docteur  Bancroft,  qui  s*est  occupe  avec  beaucoup  de 
succes,  de  la  teinture,  a  bien  cherch6  indiquer  ce  qui  se  passe  dans 
la  formation  de  cette  couleur,  mais  comme  son  opinion  ne  nous 
paroit  appuyee  sur  aucune  experience,  nous  n*en  devions  pas  moins 
regarder  cette  question  comme  aussi  peu  avancee  qu*elle  Tetoit 
avant  la  publication  de  son  travail."  Ann.  de  Chimie,  torn.  75.  p. 
288. 


SS9  Philosophy  of  Permanent  Colours. 

let  colour  (instead  of  a  rose  or  crimson)  by  the  common 
process,  is  due  to  the  action  of  the  acid  of  tartar,  and  as 
this  is  precisely  what  I  had  distinctly  asserted  and  main- 
tained sixteen  years  before,  I  must  understand  them  not 
as  intc  ding  to  controvert  my  opinion,  but  to  represent 
it  as  one  which,  though  correct,  had  been  formed  or  ha- 
zarded^ without  any  experiment  or  evidence;  and  that, 
therefore,  what  I  had  done,  was  of  little  or  no  value, 
and  that  they  were  alone  entitled  to  the  credit  of  having 
ascertained  and  established  an  important  fact. 

Not  finding  in  mvself  any  desire  to  conceal,  overlook, 
or  undervalue  the  labours  of  others,  to  render  my  own 
more  important,  I  am  unwilling  to  suspect  that  desire  in 
these  gentlemen;  but  I  can  only  avoid  doing  so,  by  sup- 
posing that  when  they  ventured  to  represent  me  as  having 
made  no  experiment  on  this  subject,  they  were  not  only 
ignorant  of,  but  culpably  negligent  in  ascertaining  the 
truth,  as  they  might  have  done  by  recurring  to  the  state- 
ments between  pages  284  and  288  of  the  volume  publish- 
ed in  1794,  (now  reprinted  between  pages  352  and  355 
of  this  volume,)  which  abundantly  manifest  that  the  opi- 
nion in  question,  was  not  only  supported,  but  had  been 
forced  upon  me,  by  a  great  number  of  decisive  experi- 
ments. 

Broadcloths,  as  commonly  manufactured,  vary  in  width 
from  60,  to  63  inches;  and  they  vary  also  considerably  in 
substance  or  weight.  Of  three  samples  of  scarlet  broad- 
doth  which  I  weighed,  the  heaviest,  said  to  be  Mr.  Nash's, 
was  equal  to  one  pound  eight  and  one  half  ounces  per 
yard,  and  the  lightest  to  one  pound  two  ounces  and  one- 
tenth.  Cloths  when  dyed  of  the  greater  part  of  the  colours 
in  use,  shrink  and  acquire  weight;  but  when  dyed  scarlet, 
they,  by  reason  of  the  action  of  the  acids  employed,  be- 
come of  less  xvcight,  and  each  piece  is  made  a  yard  or 
two  longer;  the  effect  oi  fidlin^^  being  in  some  degree 


Philosophy  of  Permanent  Colours,  S89 

undone;  and  when  so  lengthened,  they  are  said  to  be 
leached. 

Having  thus  communicated  the  results  of  my  obser- 
vations on  the  uses  of  tin,  in  various  combinations,  as  a 
mordant  upon  wool  with  the  cochineal  colouring  matter, 
it  remains  for  me  to  state,  as  shortly  as  possible,  the  ef- 
fects of  other  bases  with  the  same  colouring  matter  also 
upon  wool  or  woollen  cloth. 

Cochineal  with  nitro- muriate  of  platina,  dyed  a  red; 
which,  by  the  addition  of  carbonate  of  lime,  became  a 
chesnut  colour. 

With  nitro-muriate  of  gold,  it  dyed  a  reddish  brown. 
With  nitrate  of  silver,  a  dull  red;  and  with  muriate  of 
silver,  a  lively  reddish  orange. 

With  the  acetite  of  lead,  a  purple,  inclining  to  the  vio- 
let; and  with  nitrate  of  lead,  a  delicate  lively  colour,  be- 
tween the  red  and  cinnamon,  but  inclining  most  to  the 
former.  A  little  murio  sulphate  of  tin,  added  to  the  li. 
quor  in  which  this  last  was  dyed,  soon  changed  it  to  a 
good  crimson. 

With  either  the  sulphate,  nitrate,  muriate,  or  acetate  of 
iron,  cochineal  produces  a  dark  violet,  and  even  a  full 
black  colour,  when  employed  in  sufficient  quantity. 

All  the  preparations  of  copper  appear  to  sadden  and 
debase  the  colouring  matter  of  cochineal;  and  all  those 
of  mercury,  which  I  have  tried,  do  this  in  much  greater 
degrees;  most  of  them,  whilst  they  debase  the  colour, 
seem  to  annihilate  or  render  latent  a  considerable  part 
of  it. 

With  nitrate  of  zinc,  cochineal  dyed  a  lively  strong 
lilac  colour  approaching  nearly  to  purple;  and, 

With  muriate  of  zinc,  a  colour  like  the  preceding,  but 
inclining  a  little  more  to  the  purple.  Probably  the  iron 
usually  contained  in  zinc  may  have  contributed  in  these 
instances  to  incline  the  cochineal  crimson  so  much  to  the 


390  Fliilosophy  of  Permanent  Colours. 

blue  or  violet  shades,  since  an  oxide  of  zinc,  in  some 
very  pure  lapis  caliininaris,  being  dissolved  by  muriatic 
acid,  dyed  (with  cochineal)  a  scarlet,  but  little  inferior  to 
that  commonly  produced  with  the  nitro-muriate  of  tin  and 
tartar,  except  in  being  a  little  more  yellow;  and  upon  add- 
ing a  little  murio-tartrite  of  tin  to  the  dyeing  liquor,  it 
soon  produced  a  good  scarlet.  The  pure  oxide  of  zinc, 
therefore,  seems  to  approach  nearest  to  that  of  tin,  in  ex- 
alting the  colouring  matter  of  cochineal;  though  I  believe 
the  colours  resulting  from  it  are  less  durable  than  those 
with  the  basis  of  tin. 

With  different  solutions  of  bismuth,  cochineal  produ- 
ced various  shades  of  lilac;  some  of  them  very  lively  and 
delicate;  but  all  preparations  of  this  semi-metal,  instead 
of  displaying  and  exalting  the  cochineal  colour,  tended  to 
render  a  part  of  it  latent.  The  oxide  of  bismuth,  dissolv- 
ed in  strong  vinegar,  did  this  less  than  most  of  the  other 
preparations;  it  dyed  with  cochineal  a  pretty  good  pur- 
ple, and  the  murio-sulphate  of  bismuth,  a  salmon  co- 
lour. 

With  nitrate  of  cobalt,  cochineal  dyed  a  good  purple, 
and  a  violet  with  the  sulphate  of  that  metal. 

With  nitrate  of  nickel,  a  dark  lilac,  inclining  to  the 
violet. 

With  yellow  oxide  of  tungsten,  cochineal  dyed  a  red 
much  like  that  commonly  obtained  from  madder. 

With  sulphate  of  manganese,  an  orange;  and, 

With  the  nitrate  of  manganese,  a  colour  resembling  the 
madder  red. 

With  crude  antimony,  which  had  been  subjected  to  the 
action  of  nitric  acid,  cochineal  dyed  a  scarlet  very  much 
like  that  dyed  w  ith  lapis  caliminaris  dissolved  by  muriatic 
acid,  and  but  little  inferior  to  the  best  scarlets  given  w^ith 
the  tin  basis;  and. 

With  Macquer's  arsenical  neutral  salt,  or  the  acidu- 


Philosophy  of  Permanent  Colours*  391 

lous  arseniate  of  potash,  cochineal  dyed  a  lively  good 
purple;  and  with  common  white  arsenic  a  full  dark  lilac 
colour. 

Such  were  the  effects  of  different  metallic  bases,  in  dye- 
ing with  cochineal  on  woollen  cloth.  Of  the  simple  earths 
I  have  only  tried  alumine  and  silex  as  bases  with  cochi- 
neal. Those  of  Zircon,  Glucine,  (or  Glycine,)  and  Yttria 
(or  according  to  Dr.  Young,  Ittria,)  being  too  rare  and 
costly  for  this  use. 

The  effects  of  sulphate  of  alumine,  or  common  alum, 
with  cochineal,  and  especially  in  dyeing  crimson,  are  well 
known.  Alumina,  or  earth  of  alum,  (obtained  by  decom- 
posing and  precipitating  it  by  potash  from  water,  satu- 
rated with  alum,)  when  thoroughly  washed,  dried,  and 
finely  powdered,  did  not  seem  capable,  in  repeated  trials, 
of  alone  fixing  or  serving  as  a  basis  of  the  cochineal  co- 
lour on  wool.  In  this  respect  it  differed  from  the  powdered 
calx  of  tin. 

But  the  powdered  alumine,  being  boiled  up  with  cream 
of  tartar,  was  so  far  dissolved  by  its  acid,  that  with  co- 
chineal it  dyed  a  good  crimson,  though  not  much  better 
than  that  which  may  be  produced  with  the  sulphate  of 
alumine. 

The  same  powdered  earth  of  alum,  dissolved  by  lemon 
juice,  dyed  with  cochineal  a  very  good  rich  full  crimson. 

The  same  powdered  earth  of  alum  dissolved  by  nitric 
acid,  (and  forming  nitrate  of  alumine,)  produced  a  good 
red,  inclining  to  the  crimson. 

The  same  dissolved  in  muriatic  acid,  (muriate  of  alu- 
mine,) dyed  a  crimson,  differing  but  little  from  that  pro- 
duced with  common  alum. 

The  silicated  alkali  of  Dr.  Black,  or  powdered  flints, 
dissolved  by  a  violent  heat  in  a  crucible,  with  pure  caus- 
tic alkali  or  potash,  was  tried  as  a  basis  for  the  cochineal 
colour.  At  first,  the  fibres  of  the  cloth  did  not  seem  to 


392  Philosophy  of  Permanent  Colours, 

have  sufficient  attraction  for  the  siliceous  basis  and  the 
colouring  matter,  to  attach  and  fix  them  properly;  but 
on  adding  a  little  sulphuric  acid,  so  as  to  decompose  and 
neutralize  a  part  of  the  alkali,  which  had  dissolved  and 
was  combined  with  the  siliceous  earth,  the  colour  took 
freely,  and  rose  to  a  full,  rich,  pleasing  purple,  in  which 
the  red  or  crimson  predominated  considerably;  and  this 
colour  afterwards  proved  sufficiently  durable. 

In  regard  to  alkaline  earths,  (so  called,)  I  found  that 
lime-water  with  cochineal  dyed  a  purple,  which  took  but 
slowly,  and  required  long  boiling. 

That  sulphate  of  lime,  or  lime  dissolved  by  sulphuric 
acid,  dyed  a  full  dark  red. 

That  nitrate  of  lime,  or  lime  dissolved  by  nitric  acid, 
dyed  a  lively  red,  approaching  to  scarlet. 

And  that  muriate  of  lime  with  cochineal  dyed  a  pur- 
ple. 

Cloth  boiled  in  water  with  nitrate  of  lime,  and  then 
dyed  in  clean  water  with  cochineal  and  tin,  dissolved  by 
aqua-fortis  and  tartar  mixed,  received  a  good  scarlet. 

Cloth  boiled  with  carbonate  of  lime  and  alum,  and  then 
dyed  in  clean  water  with  cochineal,  took  a  good  crimson, 
inclining  to  the  bluish  shade. 

Sulphate  of  barytes,  or  ponderous  spar,  not  being  solu- 
ble in  water,  was  not  tried. 

But  muriate  of  barytes,  employed  as  a  basis  for  the 
cochineal  colour,  dyed  a  good  lively  purple;  and 

Nitrate  of  barytes  dyed  a  colour  nearly  similar,  but 
inclining  a  little  more  to  the  crimson. 

Magnesia  alone  did  not  combine  sufficiently  with  the 
fibres  of  cloth,  and  with  the  colouring  matter  of  cochineal, 
to  serve  as  a  basis  for  dyeing. 

But  magnesia  dissolved  by  sulphuric  acid,  (forming 
Epsom  salt,)  dyed  a  lively  purple  with  cochmeal,  though 


Philosophy  of  Permanent  Colours*  393 

it  took  but  slowly,  and  required  long  boiling.  The  ace- 
tate of  magnesia  dyed  a  lilac  colour. 

Strontites,  or  strontia  earth,  dissolved  by  muriatic  acid, 
and  employed  as  a  mordant  with  cochineal,  produced  on 
woollen  cloth  an  orange  colour. 

It  appears,  therefore,  that  besides  the  metallic  oxides 
and  solutions,  the  simple  earths,  so  far  as  they  have  been 
tried,  and  all  the  alkaline^  are  capable  of  serving  as  bases 
of  the  cochineal  colouring  matter,  though  not  with  equal 
advantage;  and  we  shall  hereafter  find,  that  they  are  ca- 
pable of  doing  the  same  to  other  adjective  colours;  a  fact 
never  before  ascertained,  though  of  great  importance,  as 
well  in  respect  of  the  practical  improvements  which  it 
may  produce,  as  of  the  general  principles  and  conclusions 
to  which  it  may  lead  us  on  this  subject.* 

I  have  repeated  nearly  all  the  foregoing  experiments 
with  silk,  instead  of  wool,  and  generally  with  effects  less 
advantageous.  Cochineal,  indeed,  with  the  aluminous  ba- 
sis, dyes  the  crimson  colour  as  well  and  as  durably  on 
silk  as  on  wool,  and  the  modes  of  producing  a  very  last- 
ing crimson  by  these  means  are  well  known.  But  the 
oxides  or  solutions  of  tin  tend  to  diminish  the  shining 
glossy  appearance  of  silk,  and  therefore,  when  applied  to 
it,  do  not  reflect  the  cochineal  colour  with  the  same  de- 
gree of  fulness  and  lustre  as  upon  wool;  and  it  has,  there- 
fore, been  found  impossible  to  dye  a  good  lively  scarlet 
on  silk  by  the  means  which  communicate  that  colour  to 
wool. 

*  I  have  found  that  cochineal  has  so  much  affinity  for  wool,  that 
if  the  latter  be  boiled  with  a  portion  of  sulphuric  acid  sufficiently 
diluted,  and  afterwards  dyed  with  cochineal,  it  will,  without  any 
other  basis,  take  a  red  colour,  capable  of  bearing  exposure  to  the 
sun  and  air  for  some  weeks,  though  fewer  than  if  dyed  upon  a  suit- 
able basis.  But  cotton  will  take  no  colour  in  this  way. 

Vol.  I.  3D 


394  Philosophy  of  Permanent  Colours. 

The  late  Mons.  Macquer,  indeed,  about  the  year  1768, 
pretended  to  have  discovered  the  means  of  dyeing  a  scar- 
let upon  silk  by  a  process  which  he  published  in  the  Me- 
moirs of  the  Royal  Academy  of  Sciences  for  that  year. 
According  to  that  process,  he  began  by  dyeing  the  silk 
first  of  a  yellowish  orange  colour,  with  annotta  applied  in 
the  usual  way;  then  he  soaked  it  for  half  an  hour  in  a  dilu- 
ted solution  of  tin,  made  by  a  mixture  of  two  parts  of  the 
nitric  with  one  of  the  muriatic  acid;  after  which  the  silk  was 
taken  out,  moderately  pressed,  and  rinced  in  clean  water, 
though  he  afterwards  found  it  better  to  omit  the  rincing. 
To  dye  the  silk,  when  thus  impregnated  with  nitro-mu- 
riate  of  tin,  he  prepared  a  bath,  by  boiling  from  two  to 
four  ounces  of  cochineal  and  a  quarter  of  an  ounce  of 
cream  of  tartar,  for  each  pound  of  silk,  some  minutes  in 
water;  after  which  he  added  cold  water,  until  the  heat  of 
the  liquor  was  reduced  to  what  the  hand  could  bear,  and 
then  put  in  the  silk,  and  dyed  it  as  usual,  gradually  rais- 
ing the  heat  of  the  dyeing  liquor,  so  as  at  last  to  make  it 
boil  for  a  single  minute.  I  have  several  times  repeated 
this  process,  but  always  found  the  colour  produced  by  it 
very  inferior  to  the  scarlets  usually  dyed  on  woollen  cloth; 
and  M.  Berthollet  informs  us,  that  this  was  also  the  case 
at  the  trials  which  M.  Macquer  himself  made  of  his  pro- 
cess at  the  dye-house  of  the  Gobelines;  and  in  truth  there 
Mas  nothing  of  any  importance  in  Macquer's  supposed 
discovery.  It  seems,  indeed,  to  have  been  chiefly  bor- 
rowed from  a  process  published  by  SchefFer,  in  1751, 
excepting  so  far  as  relates  to  the  colour  first  given  with 
annotta,  and  excepting  a  difference  in  the  proportion  of 
muriatic  acid  for  dissolving  the  tin;  a  difference,  how- 
ever, which  did  not  render  the  solution  in  any  respect 
more  efficacious. 

If  the  murio-sulphuric  solution  of  tin,  herein  before 
described,  be  diluted  with  about  five  times  its  weight  of 


JPhiksophy  of  Permanent  Colours.  395 

water,  and  silk  be  soaked  in  it  for  the  space  of  two  hours, 
then  taken  out,  moderatf^ly  squeezed  or  pressed,  after- 
wards partly  dried,  and  then  dyed,  as  usual,  in  a  bath 
prepared  with  cochineal  and  quercitron  bark,  in  the  pro- 
portion of  four  parts  of  the  former  to  three  of  the  latter,  it 
will  receive  a  colour  approaching  very  nearly  to  a  scarlet; 
and  this  may  be  made  to  receive  more  body  by  a  farther 
slight  immersion  into  the  diluted  murio  sulphate  of  tin, 
and  a  second  dyeing  in  the  bath  with  cochineal  and  quer- 
citron bark;  and  if  afterwards  a  litde  of  the  red  colouring 
matter  of  safHower  be  superadded  by  the  usual  mode  of 
applying  it,  a  good  scarlet  may  be  produced.  By  omit- 
ting the  quercitron  bark,  and  dyeing  the  silk  (prepared  as 
before  mentioned)  with  cochineal  only,  a  very  lively  rose 
colour  will  be  produced;  and  this  may  be  yellowed  so  as 
nearly  to  approach  the  scarlet,  by  adding  a  large  pro- 
portion of  tartar  to  the  cochineal  in  the  dyeing  vessel. 

With  lime-water  as  a  mordant,  cochineal  gave  to  silk  a 
very  agreeable  purple;  with  muriate  of  barytes,  a  lively 
delicate  lilac  colour;  with  murio  sulphate  of  bismuth,  a 
salmon  colour;  and  with  nitrate  of  cobalt,  a  very  lively 
and  beautiful  purple;  with  nearly  all  the  other  metallic 
and  earthy  bases  cochineal  produced  similar,  but  paler 
colours  on  silk  than  on  wool. 

The  scarlet  dye  is  still  less  applicable  to  cotton  than  to 
silk,  there  being,  unfortunately,  but  a  slight  affinity  be- 
tween the  former  and  the  oxide  of  tin,  even  when  united 
with  the  colouring  matter  of  cochineal.  This  was  de- 
monstrated by  the  late  M.  Dufay,  who  caused  a  piece 
of  cloth  to  be  manufactured  from  a  mixture  of  wool  and 
of  cotton,  which  having  undergone  the  usual  process  for 
dyeing  scarlet,  became,  as  he  describes  it,  *'marbree  de 
couleur  de  feu  et  de  blanc,"  (marbled  with  white  and 
fire  colours,)  the  cotton  remaining  perfectly  white,  though 
the  wool  was  dyed  scarlet:  and  he  found  a  like  want  of 


396  Philosophy  of  Permanent  Colours, 

attraction  betvvten  cotton  and  the  colouring  matters  of 
kermts  and  stick  lac.  He  morever  found  that  a  skein  of 
while  woollen  yarn,  and  another  of  cotton,  being  at  the 
same  time,  and  in  an  equal  degree,  submitted  to  the  ac- 
tion of  the  same  preparation,  and  dyeing  liquors,  which 
are  commonly  employed  lor  scarlet,  the  woollen  yarn 
received  a  beautiful  scarlet,  or,  as  he  terms  it,  '■^ fire 
colour^'*'*  whilst  the  cotton  remained  as  white  as  at  first.* 
Similar  effectsf  have  frequently  occurred  to  me,  and  I 
have  clearly  perceived  them  to  arise,  not  because  the  cot- 
ton is  not  capable  of  imbibing  the  scarlet  dye;  but  be- 
cause, having  a  weaker  attraction  for  it  than  that  which 
wool  exerts  on  the  particles  of  that  dye,  the  latter  draws, 
and  exclusively  appropriates  to  itself^  all  the  colour  con- 
tained in  the  dyeing  liquor;  though  when  cotton  is  sub- 
jected to  the  same  process  by  itself,  freed  from  the  inter- 
ference of  a  superior  attraction  from  wool,  it  takes  a  scar- 
let colour,  as  I  know  by  repeated  trials,  more  slowly,  in- 
deed, and  paler,  than  tiiat  which  is  usually  imbibed  by 
woollen  cloth.  It  is,  perhaps,  owing  to  this  weaker  attrac- 
tion between  the  fibres  of  cotton,  and  the  scarlet  dye,  that 
the  latter  is  so  much  less  permanent  on  cotton  than  on 
wool;  and  it  is  also  from  this  want  of  sufficient  attraction, 
that  the  cochineal  colour  is  found  to  take  most  bencfi- 

*  See  Mem.  de  TAcad   Ro.  des  Sciences,  &c.  1737. 

t  In  the  dyeing  of  scarlet,  it  is  every  day  seen,  that  pieces  of 
woollen  cloth  or  stuff,  having  at  each  edge  a  narrow  longitudinal 
stripe,  formed  by  an  intermixture  of  cotton  yarn,  after  being  im- 
pregnated in  the  usual  way  with  the  mordant  or  oxide  of  tin,  will 
attract  and  imbibe  the  colouring  particles  of  cochineal,  so  as  to  ex- 
haust the  dyeing  liquor,  and  sometimes  leave  it  perfectly  colourless, 
and  become  scarlet  in  every  purt,  excepting  the  stripes  formed  of 
coiton-yarn,  which  always  come  out  of  the  dyeing  liquor  without 
the  smallest  tinge  or  change  of  colour,  though  both  the  mordant 
and  the  particles  of  cochineal  are  applied  to  the  latter  equally 
with  the  other  parts  of  the  cloth. 


Philosophy  of  Permanent  Colours.  397 

cially  on  cotton,  v\  hen  the  basis  has  been  first  applied 
separately, 

SchcUer,  in  1751,  recommended  the  dyeing  of  scarlet 
on  cotton  in  this  way,  by  first  soaking  it  in  a  diluted  ni- 
tro- muriate  of  tin,  and  afterwards  dyeing  it  with  cochi- 
neal; but  the  colour  being  fugitive,  little  or  no  use  was 
ever  made  of  the  process;  though  the  late  Dr.  Berken- 
hout  probably  availed  himself  of  it  some  years  afterwards, 
when  he  pretended  to  have  discovered  the  means  of  dve- 
ing  "  scarlet,  crimson,  and  other  colours,  upon  cotton  and 
linen;"  and  though  his  process  was  not  materially  dif- 
ferent from  that  of  SchtrfFer,  nor  in  any  respect  preferable 
to  it,  he  found  means  to  obtain  5000/.  sterling  from  the 
British  government,  as  a  reward  for  making  it  public* 

*  Dr.  Berkenhout's  process  having,  I  believe,  never  been  pub- 
lished, I  shall  subjoin  the  account  of  it,  which  was  "communicated 
by  order  of  the  Lords  of  the  Treasury  to  the  Company  of  Dyers  in 
the  City  of  London,  the  26th  of  August,  1779;"  viz. 

**  Cotton  or  linen,  either  in  yarn  or  the  piece,  should  be  perfectly 
■wet  with  hot  water,  and  then  wrung  out,  as  is  the  common  practice. 

"  This  being  done,  it  must  be  perfectly  soaked  in  a  solution  of 
tin,  diluted  with  an  equal  quantity  of  clear  soft  water. 

"  I  he  cotton  or  linen  being  so  far  prepared,  must  be  wrung  out, 
but  not  forcibly;  then  it  is  to  be  nearly  dried,  laying  horizontally 
upon  a  hurdle,  with  a  double  linen  sheet  between  and  covered  with 
the  same. 

"  The  solution  of  tin  being  for  scarlet,  must  be  made  of  nitrous 
acid,  and  not  of  aqua-ibrtis;  but  for  crimson,  aqua-fortis  must  be 
used;  and  the  bloom  is  to  be  given,  after  it  comes  out  of  the  dye,  by 
a  small  quantity  of  sal-ammoniac  and  pearl  ashes,  dissolved  per- 
fectly in  warm  water;  but  this  water  must  not  be  more  than  milk- 
warm. 

"  The  colouring  vat,  for  the  scarlet  or  crimson,  is  simply  cochi- 
neal in  water,  no  hotter  than  the  hand  will  bear;  and  as  vegetable 
matter  receives  only  the  small  particles  of  the  colour  from  the  na- 
ture of  its  pores,  two  ounces  to  a  pound  of  the  materials  dyed  may 
be  necessary;  but  cotton  or  linen,  fresh  prepared,  will  draw  from 


398  Philosophy  of  Permanent  Colours, 

But  as  no  use  ever  has  been,  or  is  likely  to  be  made  of 
this  supposed  discovery,  I  must  hope,  and,  indeed,  I 
think  it  probable,  that  the  Doctor  had  some  better  claim 
to  a  national  remuneration,  though,  from  particular  con- 
siderations, it  was  not  brought  into  public  view. 

Besides  the  fugitive  nature  of  the  scarlet  dyed  by  Dr. 
Berkenhout's  process,  which,  indeed,  is  calculated  to  pro- 
duce only  a  crimson,  and  not  a  scarlet,  unless  some  yel- 
low colour  be  superadded  by  other  means  (which  he  does 
not  mention,)  it  is  liable  to  injure  the  texture  of  the  cotton 
or  linen  dyed  with  it,  because  the  nitric  calx  of  tin,  ap- 
plied as  the  basis,  constantly  absorbs  oxygene  from  the  at- 
mosphere, and  becomes  corrosive,  whereas,  in  the  present 

the  same  vat,  heated  as  before,  all  the  inferior  shades  from  scarlet 
and  crimson:  and  if  any  colour  still  remains  in  the  vat,  it  may  be 
taken  out  entirely  by  wool  prepared  in  the  usual  manner. 

"  The  same  preparation  of  tin  serves  for  the  greens  and  yellows, 
with  the  same  materials  only  that  are  employed  by  dyers,  except 
the  best  yellow,  which  is  produced  from  turmeric* 

"  It  is  necessary  to  observe,  that  after  the  preparation  has  been 
made  use  of  for  scarlet  or  crimson,  the  residue  continues  sufficiently 
strong  for  greens  or  yellows,  even  after  it  has  been  kept  a  consider- 
able time. 

«  N.  B.  To  make  the  best  solution  of  tin  with  nitrous  acid,  it  is 
necessary  to  have  the  strong  smoking  spirit,  to  which  an  equal  quan- 
tity of  the  purest  river  water  must  be  added,  and  the  proportions  of 
the  following  ingredients,  are  to  the  weight  of  spirit,  one-sixteenth 
of  sal-ammoniac  and  one-lhirty-second  of  refined  nitre  dissolved  by 
little  at  a  time;  in  this  aqua-regia  dissolve  one-eighth  of  granulated 
tin,  also  by  small  quantities,  to  prevent  too  great  an  ebullition,  which 
would  weaken  the  solution  considerably.  The  ingredients  and  pro- 
portions are  the  same,  when  a  solution  is  to  be  made  with  aqua-for- 
tis;  but  that  spirit,  in  general,  will  not  bear  any  water  when  a  per- 
fect solution  is  intended." 


*  Nothinj^  can  be  more  erroneous  tlian  this  and  several  of  Dr.  Berkenhout's 
other  observations. 


Philosophy  of  Permanent  Colours.  399 

case,  this  effect  cannot  be  counteracted  by  occasional 
washings  with  soap. 

Mr.  Henry  says,  that  '*  if  a  scarlet  could  be  dyed  with- 
out the  use  of  nitrous  acid,  the  tin  basis  might  be  em- 
ployed for  this  purpose  on  cotton;  but  that  acid  being  re- 
quisite  for  the  production  of  this  beautiful  colour^  and  be- 
ing highly  corrosive  to  colours,  this  basis  is  prevented 
from  being  applied  to  that  substance." — Here  this  inge- 
nious chemist  appears  to  have  fallen  into  the  universal 
error  of  believing,  that  nothing  but  a  solution  of  tin  by 
nitric,  or  nitrous  acid,  can  dye  a  scarlet  colour  with  co- 
chineal. 

If,  notwithstanding  the  want  of  sufficient  permanency 
in  the  scarlet  colour  dyed  with  cochineal  upon  cotton,  it 
should  be  deemed  proper  to  apply  it  to  that  substance, 
the  best  way  of  doing  this  which  I  have  yet  found,  is,  to 
soak  the  cotton,  (previously  moistened,)  for  about  half 
an  hour  in  a  diluted  murio-sulphuric  solution  of  tin,  as 
proposed  for  silk;  then  wring  or  press  out  the  superflu- 
ous part  of  the  solution  of  tin,  and  plunge  the  cotton  into 
water,  in  which  as  much,  or  nearly  as  much,  clean  pot- 
ash or  soda  has  been  dissolved  as  will  neutralize  the  acid 
still  adhering  to  the  cotton,  so  as  thereby  to  decompose 
the  oxide  of  tin,  and  cause  it  to  be  more  copiously  de- 
posed or  fixed  in  or  upon  the  fibres  of  the  cotton,  which, 
being  afterwards  rinced  in  clean  water,  may  be  dyed  with 
cochineal  and  quercitron  bark,  in  the  proportions  of  about 
four  pounds  of  the  former  to  two  and  a  half  or  three 
pounds  of  the  latter.  A  full  bright  colour  may  be  given 
to  cotton  in  this  way,  which  will  bear  a  few  slight  wash- 
ings with  soap,  and  a  considerable  degree  of  exposure  to 
air.  Indeed,  the  yellow  part  of  the  colour  obtained  from 
quercitron  bark  will  even  bear  long  boiling  with  soap,  as 
well  as  the  application  of  strong  acids,  without  injury. 

Cotton  impregnated  or  printed  with  the  aluminous 


400  Philosophy  of  Permanent  Colours, 

mordant,  as  commonly  applied  by  calico-printers  for 
madder  reds,  will,  if  dyed  with  cochineal,  receive  a  very 
beautiful  crimson  colour,  capable  of  bearing  several  wash- 
ings, and  of  resisting  the  weather  for  some  time,  though 
not  long  enough  to  deserve  the  appellation  of  a  fast  co- 
lour. I  think,  however,  that  it  is  advantageous  for  caHco- 
printers,  in  dyeing  madder  reds  upon  the  finer  cottons  or 
muslins,  to  add  also  a  little  cochineal,  the  crimson  colour 
of  which  is  admirably  calculated  to  overcome  the  yellow- 
ish hue  that  degrades  the  madder  reds,  and  arises  from  a 
portion  of  that  particular  colouring  matter  which  produces 
the  fauve^  or  fawn  colour,  herein  before  mentioned.  By 
this  addition,  the  madder  reds  are  rendered  much  more 
beautiful,  so  long  as  any  part  of  the  cochineal  crimson  re- 
mains, and  afterwards  they  are  no  worse  than  if  it  ha^ 
never  been  applied. 

Cotton  printed  with  iron  liquor  takes  a  very  full  black 
when  dyed  with  cochineal;  but  I  found  this  less  durable 
than  the  same  colour  dyed  from  much  cheaper  matters. 
A  great  variety  of  other  colours  may  be  dyed  upon  cot- 
ton impregnated  with  different  metallic  or  earthy  bases; 
but  as  better  colours  may  be  more  cheaply  given  by 
other  means,  I  shall  offer  no  farther  explanations  respect- 
ing them. 

A  strong  decoction  of  cochineal,  thickened  with  gum, 
and  mixed  with  a  suitable  proportion  of  nitrate  of  alu- 
mine,  being  penciled  upon  cotton  as  a  pro-substantive  co- 
lour, afforded  a  very  full  beautiful  colour  between  the  scar- 
let and  crimson,  which  stood  some  washings,  and  a  con- 
siderable degree  of  exposure  to  weather.  Several  of  the 
different  solutions  of  tin  being  employed,  instead  of  the 
nitrate  of  alumine,  as  well  as  conjointly  with  it,  produced 
very  beautiful  rose  colours,  approaching  more  or  less  to 
the  scarlet;  and  by  adding  a  small  proportion  of  the  quer- 
citron bark,  they  were  made  scarlet.  They  could  not,  in- 


Philosophy  of  Permanent  Colours.  401 

deed,  be  considered  as  fast  colours,  but  had  the  advan- 
tage  of  being  very  beautiful,  and  less  fugitive  than  many 
of  those  which  are  too  frequently  employed  by  calico- 
printers,  under  the  denomination  of  chemical  colours. 

Since  the  preparation  or  manufacture  of  Morocco 
leather  has  been  established  in  this  country,  cochineal  is 
employed  to  communicate  the  beautiful  colour  of  that^ 
which  is  called  red  Morocco;  though  in  Persia,  Arme- 
nia, Barbary,  and  the  Greek  Islands,  a  similar  colour 
was  originally  produced  by  the  use  of  either  kermes  or 
lac.  As  a  basis  for  the  colouring  matter  of  cochineal, 
goat-skins  deprived  of  their  hair  by  lime  water,  and  pro- 
perly cleansed,  are  impregnated,  on  that  which  was  the 
hairy  side,  with  a  saturated  solution  of  alum,  applied  re- 
peatedly and  equally  by  a  sponge,  and  after  an  interval 
of  three  or  four  days,  a  decoction  of  cochineal,  which  has 
been  strained,  is  applied  also  by  a  sponge,  to  the  same 
side  or  surface,  a  little,  but  not  much,  more  than  blood- 
warm,  least  it  should  crisp  the  leather.  This  application 
is  repeated  from  time  to  time,  until  a  colour  sufficiently 
full  and  equal  has  been  produced.  Afterwards  the  skins 
are  soaked  in  bran  liquor,  and  then  tanned  by  a  decoction 
of  either  galls  or  sumach,  or  of  both  mixed  together. 

I  have  found  that  by  substituting  a  diluted  murio-sul- 
phate  of  tin,  for  the  solution  of  alum,  or  by  employing  a 
mixture  of  both  upon  goat-skins  in  a  suitable  state  of 
preparation,  the  colour  subsequently  produced  was  con- 
siderably improved,  at  least  in  vivacity. 

Having  nothing  more  of  importance  to  communicate 
respecting  cochineal,  I  shall  here  finish  this  chapter,  and 
in  so  doing,  make  an 

END  OF  THE  FIRST  VOLUME. 


\T. 


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